BSNL

1. The 7 layers of OSI model are:

1. The Application Layer: Application layer is responsible for identifying and establishing the availability of desired communication partner and verifying sufficient resources exist for communication. Some of the important application layer protocols are: WWW, SMTP, FTP, etc.

2. The Presentation Layer: This layer is responsible for presenting the data in standard formats. This layer is responsible for data compression, decompression, encryption, and decryption. Some Presentation Layer standards are: JPEG, MPEG, MIDI, PICT, Quick Time, TIFF.

3. The Session Layer: Session Layer is responsible for co-ordinating communication between systems/nodes. The following are some of the session layer protocols and interfaces: a) Network File System (NFS), SQL, RPC (Remote Procedure Call), X-Windows, ASP, DNA SCP.

4. The Transport Layer: The Transport Layer is responsible for multiplexing upper-layer applications, session establishment, and tearing-down of virtual circuits. This layer is responsible for flow control, to maintain data integrity.

5. The Network Layer: There can be several paths to send a packet from a given source to a destination. The primary responsibility of Network layer is to send packets from the source network to the destination network using a pre-determined routing methods. Routers work at Network layer.

6. The Data Link Layer:

Data Link Layer is layer 2 of OSI reference model. This layer is divided into two sub-layers:

A. Logical Link Control (LLC) sub-layer.

B. Media Access Control (MAC) sub-layer.

The LLC sub-layer handles error control, flow control, framing, and MAC sub-layer addressing.

The MAC sub-layer is the lower of the two sub-layers of the Data Link layer. MAC sub-layer handles access to shared media, such a Token passing or Ethernet.

7. Physical Layer: The actual flow of signals take place through Physical layer. At Physical layer, the interface between the DTE and DCE is determined. The following are some of the standard interfaces are defined at Physical layer: EIA/TIA-232, EIA/TIA-449,V.24,V.35,X.21,G.703,HSSI (High Speed Serial Interface).

2. Internetwork IP addressing:

IP addresses are written using decimal numbers separated by decimal points. This is called dotted decimal notation of expressing IP addresses.

The different classes of IP addresses is as below:

Class	Format	Leading Bit pattern	Network address Range	Maximum networks	Maximum hosts/ nodes
A	N.H.H.H	0	0-126	127	16,777,214
B	N.N.H.H	10	128-191	16,384	65,534
C	N.N.N.H	110	192-223	2,097,152	254

- Network address of all zeros means "This network or segment".

- Network address of all 1s means " all networks", same as hexadecimal of all Fs.

- Network number 127 is reserved for loop-back tests.

- Host (Node) address of all zeros mean "This Host (Node)".

- Host (Node) address of all 1s mean "all Hosts (Nodes) " on the specified network.

3. The range of numbers from 224.0.0.0 to 239.255.255.255 are used for multicast packets. This is known as Class D address range.

4. Subnetting is nothing but creating networks within a network. Subnetting allows an organization with a single IP address (Class A /ClassB /ClassC) to have multiple subnetworks, thus allowing several physical networks within the organization.

Default subnet mask for Class A network: 255.0.0.0

Default subnet mask for Class B network: 255.255.0.0

Default subnet mask for Class C network: 255.255.255.0

5. 127.0.0.1 is the local loop back address.

6. In an internetwork, the number of distinct IPs' required are

1. One each per client computer

2. One each per server computer

3. One each per router interface.

For example, your network has 2 servers, 26 clients machines, and 2 router interfaces the total number of IP addresses required are 30.

7. The directed broadcast should reach all Hosts on the intended network (or subnet, if sub netted). For example, the directed broadcast address for an IP network 196.233.24.15 with default subnet mask is 196.233.24.255. This is arrived by putting all 1s for the host potion of the IP address.

8. Telnet, FTP, and TFTP:

1. Telnet is used for terminal emulation that runs programs remotely. Telnet uses TCP/IP protocol.

2. Telnet requires a username and password to access.

3. FTP (File Transfer Protocol) is a connection oriented protocol. It uses TCP/IP for file transfer. Compare this with TFTP (Trivial File Transfer Protocol) that uses UDP (Connectionless protocol). SNMP uses UDP over IP. Tracert, Ping use ICMP as their base protocol. FTP is used to transfer files.

4. Both FTP and Telnet are client-server protocols. Note that TCP/IP is a client server oriented protocol.

9. The port numbers used by different programs are as below:

I. FTP : Port #21

II. Telnet: Port #23

III. SMTP: Port #25

IV. SNMP: Port #161

It is important to know that FTP, Telnet, SMTP use TCP; whereas TFTP, SNMP use UDP.

10.

SNMP is part of TCP/IP protocol suite. It allows you to monitor and manage a network from a centralized place by using SNMP Manager software. The systems or devices that provide the responses are called agents (or MIBs). An SNMP agent is any computer running SNMP agent software.

MIB stands for Management Information Base. It is part of SNMP agent database. A MIB records and stores information abut the host it is running on. An SNMP manager can request and collect information from an agent's MIB. Routers are typical MIB agents. SNMP agent generates "trap" messages that are then sent to an SNMP management console, which is a trap destination.

11. Repeaters, Bridges, and Routers

I. Repeaters work at Physical layer (Layer 1),

II. Bridges and simple switches work at Data Link Layer (Layer 2),

III. Routers work at Network Layer (Layer 3) of ISO Reference Model.

12.            1.     The term "Segments" is usually associated with Transport layer

2.     The term "Packets" is usually associated with Network Layer and

3.     The term "Frames" is usually associated with Data Link Layer

13. Spanning Tree Protocol (STP) IEEE Specification 802.1d is used to prevent routing loops. In Cisco Catalyst 5000 series switches, use BDPUs (Bridge Protocol Data Units) to determine the spanning tree topology. STP uses a Tree Algorithm (STA) to prevent loops, resulting in a stable network topology.

14. HTTP is the protocol used for accessing the World Wide Web services. HTTP operates over TCP/IP. TCP/IP is the protocol, which is used by all internet applications such as WWW, FTP, Telnet etc.   IPX/SPX is proprietary protocol stack of Novell NetWare.

15. TCP: TCP is a full-duplex, connection-oriented protocol. It incorporates error checking as well.

UDP (User Datagram Protocol): UDP is a thin protocol. UDP is a connectionless protocol. It doesn't contact the destination before sending the packet and doesn't care whether the packet is reached at the destination. UDP uses port number 6.

The port number used by TCP is 6 and that of UDP is 17.

16. Standard adopted for Ethernet CSMA/CD by IEEE Committee is 802.3. 100BaseT (Fast Ethernet) uses IEEE803.2u standard which incorporates CSMA/CD protocol.

17.

Standard Compliance

802.3 standard for 10BaseT Ethernet CSMA/CD

802.3u IEEE standard for 100BaseT (Fast Ethernet) incorporating CSMA/CD protocol.

802.3z IEEE standard for Gigabit Ethernet

802.5 IEEE standard for Token Ring networks

802.11 IEEE standard for wireless LAN

18. Given below are the distance limitations of Fast Ethernet specification:

100BaseTX ---- Cat 5 UTP, 2 pair -------- 100 meters
100BaseT4 ----- Cat 3,4,5; UTP, 4 pair --100 meters
100BaseFX ----- MMF cable --------------- 400 meters

19. The distance specification for various media type 1000BaseXX is as given below:

1000BaseCX --- Copper shielded twisted pair---25 meters
1000BaseT------- Cat 5 UTP, 4 pair-----------------100 meters
1000BaseSX----- Multimode fiber cable -----------260 meters
1000BaseLX------ Single mode fiber cable-------- 3 km

20. 10BaseT and 100BaseT use RJ-45 type of connector. 10Base2 (also called Thinnet) uses BNC connectors for attaching work stations. BNC-T is used to connect a work station to the Thinnet coaxial cable. The BNC-T(m) connector end mates with the BNC(f) connector on the NIC card. The BNC-T(f) connector ends are attached to BNC(m) cables, that in turn attach to other computers through BNC-T connector.

21. Thicknet:

The maximum segment length of a 10Base5 Thicknet is 500 meters.

Maximum number of segments:5
Maximum segments with nodes: 3
Maximum number of repeaters: 4
Maximum overall length with repeaters: 2.5 kilometers
Maximum AUI drop cable length: 50 meters

Thicknet uses 15 pin AUI connector.

22. 10BaseT Ethernet specifies UTP cabling. UTP cabling uses RJ-45 connectors to connect the cable to the NIC (Network Interface Card).

23.

10BaseT is an example of STAR topology

10Base2 is an example of BUS topology

FDDI is an example of fiber optic network based on ring topology.

10Base2 cable uses 50 Ohm, RG-58 cable also called Thinnet.
10Base5 cable uses 50 Ohm, RG-8, or RG-11 cable also called Thicknet.

24. One of the disadvantages of 10Base2 Ethernet is that, any cable break at any point on the network may cause breakdown of the entire network.

25. Some of the important TCP/IP related diagnostic commands that need to be practiced for Network+ exam are:

Command Description

PING Used to ping the remote system (or the local host) to see that the TCP/IP connection is through.

NBTSTAT This utility displays current NetBIOS over TCP/IP connections, and display NetBIOS name cache.

NETSTAT Displays protocol statistics and current TCP/IP connections since the server was last booted.

TRACERT Used to determine which route a packet takes to reach its destination from source.

IPCONFIG Used to display Windows IP configuration information.

NSLOOKUP This utility enables users to interact with a DNS server and display resource records.

ROUTE Used to display and edit static routing tables.

26. WAN (Wide Area Network) devices extend the reach of LAN (Local Area Network) devices. WANT typically span over a wide area, such over multiple cities / countries. WANS are connected over serial lines that operate at lower speeds than LANs. Some of the WAN devices are:
1. Routers: Routers are responsible for routing the packets in an internetwork.
2. Modems: Modems connect to public telephone circuits through dial-up.
3. CSU/DSU: Stands for Channel Service Unit / Data Service Unit. CSU/DSUs are used for connecting to Central Office of a Telephone switching company and provides serial WAN connections.
4.Communication Servers: These are used for dial in/out to remote users. Provides RAS Remote Access Server) functionality.
5. Multiplexers (mux): Multiplexers combine two or more signals before transmitting on a single channel. Multiplexing can be done by sharing "time" or "frequency".

27. Routing protocols job is to maintain routing tables and route packets appropriately. Examples of routing protocols are RIP, IGRP,EIGRP,OSPF. Routers can support multiple independent routing protocols and can update and maintain routing tables for each protocol independently.
Routed protocols are used to transport user traffic from source node to destination node. Examples of routed protocols are IP, IPX, AppleTalk.

28. Both PPP and SLIP can be used for dial up connections. However, SLIP can't be used where the IP address need to be assigned dynamically. The advantage of PPP is multi protocol support, that it can support TCP/IP, IPX, AppleTalk etc. SLIP can support only TCP/IP and IP addresses need to be assigned manually.

29. Default subnet mask for Class A network: 255.0.0.0
Default subnet mask for Class B network: 255.255.0.0
Default subnet mask for Class C network: 255.255.255.0

30. The transmission speed of a T1 circuit (Used mainly in North America) is 1.544Mbps
The transmission speed of an E1 circuit (Used mainly in Europe) is 2.048Mbps.
The transmission speed of a T3 circuit (Used mainly in North America) is 44.736 mbps

2.0 Connectionless and Connection Oriented Protocols:

2.1 The following are examples of connectionless protocols:
1. IP (Internet Protocol) - IP is the network-layer connectionless protocol of TCP/IP suite.
2. UDP (User Datagram Protocol)- UDP is a connectionless transport layer protocol of TCP/IP suite.
3. Novell IPX
4. AppleTalk DDP (Datagram Delivery Protocol)
5. CLNP (Connectionless Network Service) used by DECnet

2.2 The following are examples of connection oriented protocols:
1. TCP
2. Novell SPX
3. ATM
4. X.25
5. ATP ( AppleTalk Protocol) - an Apple Talk transport layer protocol.

3.0 Token Ring:

Beaconing is used in Token Ring networks to detect and try to rectify certain network faults. By the process of Beaconing, the Token Ring network try to reconfigure by eliminating the faulty network region.

In general, network faults can be grouped into hard errors, and soft errors.
Hard errors are the those that are permanent and can not be recovered by software routines. Examples of hard errors are cable cuts and station hardware failures.
On the other hand, soft errors temporarily disrupt the network services and can be recovered by software routines.

There are two types of soft errors that are tracked by Token Ring networks:

1. Isolating faults - Isolating faults are limited to a particular fault domain. The fault domain is usually a node and its NAUN. Examples of isolating errors are: Line errors, burst errors, and internal errors.

2. Non Isolating faults- Non isolating faults are not limited to a particular fault domain. The error is likely to be spread all over the ring, like congestion. Examples of non isolating faults are: Lost frame, Token, Frequency, and congestion errors.

FDDI:

The following are the important characteristics of FDDI:

1. FDDI uses 100Mbps, dual-ring LAN and uses Token passing (Token passing mechanism is similar to Token Ring, however remember that Token Ring networks has a speed of 4 or 16 Mbps only).

2. FDDI uses fiber as the medium of transmission. Two types of fibers exist: single mode, and multi mode fibers. Single mode fiber allows much higher bandwidths and longer cable lengths compared to multi mode fiber. However, multi mode fibers are cheaper.

3. Improved security due to fiber transmission medium. It is very difficult to tap fiber transmission without being detected.

4.0 TCP/IP

4.1 TCP/IP based applications and their protocols are as described below:

1. Electronic Mail uses SMTP (Simple Mail Transfer Protocol).
2. Network Management applications use SNMP
3. Telnet uses terminal emulation
4. Distributed file services use NFS (Network File System)

4.2 Ping and Trace

During the process of network troubleshooting, you will be required to know the host or network reachability at several points of troubleshooting process. The two commands are extremely useful to check the host reachability and the path that is taken to reach the destination are 'ping' and 'trace' commands.

'Ping' command can be used to check the connectivity on AppleTalk, CLNS, Novell, and various other protocols. To perform an extended ping, simply give 'ping' at the command prompt. You will be prompted for other parameters like protocol, target IP address, etc.

The following are the possible responses for an IP ping command:
! - indicates that a reply is received
. - indicates that the router has timed out.
U - indicates that the destination is unreachable
N - indicates that the network is unreachable
P - indicates that the protocol is unreachable
? - indicates unknown packet type
Q - indicates source quench

'trace' command can be used to see the route that a packet takes to reach the destination. The trace command discovers the path taken to reach its final destination by sending out probe datagrams. The first datagram is sent out with a TTL (Time To Live) value of just 1. This causes the first router to discard the packet and send back 'time exceeded' message. Thus the first router enroute is discovered! Then, the TTL is incremented by 1 (now TTL is 2) and the datagram is sent out again. Now the second router enroute discards the packet as the TTL reached zero, and sends back 'time exceeded' message to the source. This process is repeated till the destination is reached. By doing so, the exact path that a packet takes to reach the destination is established.

TCP/IP troubleshooting:

The first step in troubleshooting TCP/IP problems is to start with the local host. You can ping the local host (use ping 127.0.0.1, a successful ping ensures that the TCP/IP stack is installed properly) and if you are successful, proceed one step at a time. The next step would be to ping the gateway or the next hop address. This procedure can be followed until you reach the destination network. Once you establish basic IP connectivity, perform any troubleshooting for higher layer protocols such as DNS resolution, FTP, or Telnet. Though it may sometimes be faster to trace route to the destination and find the problem route, it may not always be successful. It is recommended to start at the source and proceed one step at a time towards the destination network.

5.0 Router Performance:

The following are the features that affect performance on routers:
1. Queuing
2. Random Early Detection
3. Compression
4. Filtering
5. Encryption
6. Accounting

CCNP Support 642-831 Exam cram

Exam Notes

6.0 Base Lining:Baselining is the process of measuring network parameters such as network traffic, error packets, overall usage etc. Establishing a baseline when the network is performing normally enables to troubleshoot any problems introduced at a later stage. Baselining also enables network managers to plan the network expansion based on the current trend. Network monitors are useful establishing a baseline.

7.0 Cisco Network Management Tools:

Important Cisco network management tools that you need to know are:

1. Cisco Works (includes CiscoView)
2. Netsys
3. TrafficDirector
4. VlanDirector
5. WAN Manager

Note that, CiscoView is bundled with CiscoWorks. CiscoView is also available as a standalone product.

CiscoWorks: CiscoWorks is an important network management product from Cisco. It provides graphical view of Cisco device panel displays, allowing easy fault recognition and diagnosis. CiscoWorks uses SNMP (Simple Network Management Protocol) for monitoring and control of SNMP capable devices on a network. One of the big advantages of CiscoWorks is that it can be seamlessly integrated with third party SNMP network management platforms such as HP OpenView.

CiscoWorks is available in four versions:

1. CiscoWorks Blue - suitable for integrated IBM SNA and IP environments.

2. CiscoWorks Windows - A PC-based network configuration and troubleshooting tools. Suitable for small to medium size networks.

3. CiscoWorks Switched Internetwork Solutions (CWSI) - Suitable for campus LAN management. Include VlanDirector, TrafficDirector, and CiscoView.

4. CiscoWorks2000 - A web based network management suite.
Note that CWSI contains TrafficDirector application as an integral part.

Netsys: Netsys is a suite of simulation based design and troubleshooting tools. These tools allow designers to plan the network and see the network behavior before committing the designs or changes to the actual network.

TrafficDirector: By using TrafficDirector in conjunction with the embedded RMON agents allow us to measure traffic utilization, error rates, and other statistical parameters on any selected port(s).

VlanDirector: VlanDirector is a Cisco VLAN management tool. Given below are salient characteristics:
1. Graphical interface
2. Drag and drop functionality for assigning users to VLANs
3. Enables configuration, management, and monitoring of Cisco switches and routers.
4. VlanDirector can be integrated with common SNP management platforms.

WAN Manager: WAN Manager provides easy configuration, management, fault detection of wide-area multiservice networks.]

8.0 Buffers:

The following are some important terms with respect to buffers:

1. Hits: This is the count of successful attempts to allocate a buffer when required.

2. Misses: This is the count of buffer allocation attempts that resulted in increasing the buffer pool for allocating a buffer.

3. Trims: This is the count of buffers released to the system because they were not being used.

4. Created: This is the count of new buffers created in response to misses. Note that this field is displayed only for dynamic buffer pools, not for static buffer pools (ex. interface buffer pools).

5. Failures: This is the total number of allocation requests that have failed because no buffer was available. This will result in loss of datagram.

9.0 Ethernet:

Runts: This is the number of packets that have been discarded because they are smaller than the medium's minimum packet size. For Ethernet, a packet size of less than 64 bytes is considered a runt.
In the given example, there are 342 runts per 133+ million bytes. This is more than one runt per million bytes, which is acceptable. Therefore, it is likely that the network is experiencing excessive collisions.

Giants: This is the number of packets that have been discarded because they exceeded the maximum allowable size of the medium. For Ethernet, a packet size of more than 1518 bytes is considered a giant.

10.0 Some important Cisco IOS show commands:

The command 'show cdp neighbors' displays information about the Cisco devices directly connected to the router.

The command 'show cdp neighbors detail' provides additional information including network-layer protocol information.

The command 'cdp run' enables CDP. Note that CDP is enabled by default. To disable CDP, use the command 'no cdp run' in the global configuration mode.

The command 'show ip route' displays the entries in the routing table. The routes are displayed by a preceding protocol keyword. Some of the protocol keywords are:
I -IGRP; E - EGP ; B - BGP ; O - OSPF ; I - IGRP; R - RIP
The network address of the remote network, the address of the next router to the remote network, and the interface through which the remote network can be reached are provided for each route in the output. This command is widely used for diagnostic purposes for troubleshooting the routing table entries.

Exam Notes

11.0 TAC:

Two levels of access available for accessing CCO (Cisco Connection Online) are:

1. Guest access for general public. The access is limited to certain areas of CCO Website for guests.

2. Registered access for customers.

The three tools of Case management Toolkit in CCO that are accessible interact directly with TAC are:

1. Case Open - Enables you to request technical assistance by opening a case with TAC
2. Case Query - Enables you to verify the status of the case
3. Case Update - Enables you to update the case with your own information.

If a customer reports a router crash or a router hang-up to the Cisco technical support group, he may be asked to provide the outputs of the following commands:

1. Show stacks - This command displays stacks, and stack traces before the reload takes place.

2. Exception dump - The core dump is useful for obtaining a copy of memory image before router crashes. The memory image can be copied to a file by using TFTP (usually if memory dump is less than 16MB) or FTPed to a remote location. You can test the core dump by issuing the command 'write core' in privileged exec mode (enable mode). This command will cause a crash, and the content of the memory will be dumped according to the configured setup.

Cisco® has combined several important commands into one single command, for the purposes of problem reporting. The command 'show tech-support' combines several of important Cisco® commands into one single privileged command.

Cisco Technical Assistance Center (TAC) normally requires the following information when you report the case:

1. 'show running-config' command output on all routers concerned.
2. 'show version' command output on all routers concerned.
3. 'show controllers' command output on all routers concerned.
4. Details of host, servers, and network topology map
5. Network layer protocols, and version details.

12.0 SRB:

You need to configure transparent bridging or source-route bridging (SRB) to forward NetBEUI traffic to remote networks.

13.0 Cisco router encapsulation:

A Cisco router defaults to novell-ether (Ethernt_802.3). There are many encapsulation types available as given below

Common Term                    Cisco Term
Ethernet_II                             arpa
IEEE 802.3                              sap
Novell 802.3 raw                     novell-ether
SNAP                                       snap

14.0 Catalyst commands:

Some of the important Catalyst commands are:

1. Show config - This command is similar to IOS 'show running config' command.

2. Show span - This command displays information about Catalyst switched port analyzer function settings such as whether the SPAN is enabled or disabled, and whether the transmit and/or receive information is monitored. Don't confuse this with show spantree command that displays spanning tree information for a vlan.

3. Show trunk - Displays the vlan trucking information for the switch.

4. Show spantree - Displays spanning-tree information for a vlan.

5. Show spantree statistics - Displays Spanning-Tree Protocol BPDU communication in readable form.

6. Show cdp neighbors - displays CDP information about all Cisco devices connected to the switch.

Important 'show' commands for Catalyst switches that provide system settings:

1. Show system - Provides status of the system LEDs, power supplies, fan, and system among others.

2. Show test - Provides the results of diagnostic tests.

3. Show interface - Provides information on network interface flags and addressing.

4. Show module - Displays module status and information about the module.

5. Show port - A very useful command that displays information about the port and counters.

6. Show log - Displays error log.

15.0 VLANs & VTP:

A VTP capable switch can be configured as:

1. VTP server - It maintains VLAN information in a nonvolatile device or on a TFTP server.

2. Client - Clients also maintain complete list of all VLANs in the VTP domain.

3. VTP transparent mode - Switches that do not wish to participate in VTP can be put in transparent mode. Here, VTP adverts are forwarded.

A VTP advertisement necessarily consists of "Configuration revision number". Every time a VTP server updates its VLAN information, it increments the configuration revision number by one count. VTP clients, use the revision number to enforce the VLAN configuration Update.

A non-trunk port can carry only one vlan. If more than one vlan need to be carried on a single port, trunking must be enabled on that port.

The recommended maximum hop count in a VLAN is 7, that is 7 switch/router/bridge hops are allowed in a vlan. This in other words is known as the vlan diameter. Network diameter affects the network performance while doing spanning-tree computations.
Lesser the diameter of a network, faster would be the network convergence.

The following are true about VTP:

1. Switches configured in transparent mode relay VTP adverts from other switches.

2. There must be at least 1 VTP servers in a VTP management domain.

3. It is recommended to configure VTP servers ON-LINE. This would ensure VTP domain consistency.

4. VTP does not work if there is no VLAN1 or no trunk port.

5. For CWSI (CiscoWorks for Switched Internetworks) to work, VTP is required.

A vlan belongs to a specific network number. To move traffic from one vlan (one broadcast domain) to another vlan (another broadcast domain) a router is required.

Exam Notes

16.0 Troubleshooting:

The first step in troubleshooting a device is to examine the physical indicators such as LEDs. Check if there is any visual hints. This may lead to a failed power supply or disconnected cable.
The next step in diagnosing a switch problem is to check Layer 1 connectivity, and then Layer 2 connectivity. The vlan and vtp information can be obtained and diagnosed at this point.

17.0 Frame Relay:

Important 'show' command used in troubleshooting Frame-Relay networks are given below:

1. Show interfaces serial - The information provided by this command include:
- LMI type (cisco/q933a/ansi
- LMI DLCI, Keepalives, Network address and subnet mask.
- Shows the interface and line protocol conditions (Normally interface up, line protocol up)

2. Show frame-relay lmi - Provides LMI statistics.

3. Show frame-relay map: This command shows the configured dlci and ip address mapping.

4. Show frame-relay pvc: This command shows the LMI status of each configured DLCI. The packet stats for input pkts, output pkts, BECN, FECN, DE packet stats are also given.

18.0 ISDN:

ISDN can be mapped to bottom 3 layers of OSI reference model.
Layer 1 is the physical layer and the following protocols are defined at this level:

1. I.430: Defines the communication across S/T reference point.

2. I.431: Defines a full-duplex, point-to-point, serial, synchronous connection and applicable for ISDN PRI.

3. ANSI T1.601: Defines the communication across the U interface (North America only).
Layer 2 and layer 3 work for D channel only.

Layer 2 of ISDN uses LAPD (Q.921), and Layer 3 of D channel uses Q.931 which is a subset of DSS1.
B channel uses IP/IPX with HDLC/PPP/FR/LAPB protocol.

Important ISDN commands:

debug isdn q921: This debug command shows the Layer 2 D-channel activity taking place between the TE (Terminal Equipment) and the local network termination (ISDN Switch).

Debug isdn q931: This debug command shows the Layer-3 D-channel information between the local router and the ISDN switch.

Debug ppp authentication: This debug command will display CHAP and PAP authentication messages that are being exchanged.

debug bri: shows basic isdn bri routing activity. It indicates whether the ISDN code is enabling and disabling the B-channels when attempting an out going call.

show isdn status - This command outputs ISDN switch type, whether the ISDN connection is working properly. It also displays the status of Layer 1, Layer 2, and layer 3.

Show interface bri 0 - This command shows whether BRI 0 is up and whether line protocol is up (spoofing). The command also displays encapsulation method used (PPP, HDLC, or X.25).

Note that D-channel communication takes place between the TE (Usually the router) and the local network termination point (ISDN Switch). ' debug isdn q921', and 'debug isdn q931' are limited to D-channel information only. Also, 'debug isdn q921' pertains to layer-2, where as
'debug isdn q931' pertains to layer-3 (again D-channel only). These commands don't show B-channel debug information.

The BRI activation process is a 5 step process. These are:
1. The line is not active in both the directions between a TE and NT.
2. TE becomes active and sends 7E HDLC flag.
3. NT side sends frames with Activation bit (A-bit) set to 0 (indicating not activated)
4. TE synchronizes first and starts sending physical frames.
5. NT also synchronizes and starts sending frames with activation bit (A-bit) set to 1 (indicating activated)

19.0 Switching:

Netflow switching is most suitable for collecting data for accounting, billing, and charge back and other network resource utilization parameters.

20.0 Cable Testers:

Cable testers are the most basic testing tools. These are used for making sure that the physical medium is good. Cable test equipment include volt-ohm meters, multimeters, TDRs (Time Domain Reflectometers).

Exam Notes

21.0 Protocol Analyzers:

Protocol analyzer is most commonly used for recording and analyzing network protocol traffic. Filters can be set, so that only particular type of traffic is captured and analyzed. The packet content is displayed in a user friendly, and readable form by using protocol analyzers.

22.0 Debug Commands:

Debug commands are very useful for troubleshooting network problems. However, one need to be very careful when using debug command in a production network ( the term 'production network' is used in the sense that the network is in regular use, and can not be taken off without suffering some kind of loss). If the network is being used heavily, using debug command may result in the disruption of traffic and loss of data packets. Debug command, if used must be as specific as possible, to avoid unnecessary network traffic. Also, remember to undebug as soon as the purpose of using this command is achieved.

By default, all debug output is logged to the console terminal. To change the default logging option use the command 'logging <option>', the logging options include:
1. Logging console
2. Logging buffered
3. Logging monitor
4. Logging trap
Note that logging to the console produces very high overhead, whereas logging to internal buffers produces least amount of overhead compared to other logging methods.

23.0 CDP:

The following are true about CDP:

1. CDP - Cisco Discovery Protocol is a Cisco proprietary Layer 2 protocol.

2. CDP uses a multicast packet to the common destination address 01-00-0c-cc-cc.

3. CDP packets are sent out with a non zero TTL after an interface is enabled and with a zero TTL value immediately before and interface is made idle. This enables the neighboring devices to quickly discover the state of neighbors.

4. CDP packets will never be forwarded beyond the directly connected devices. To find CDP information on indirectly connected routers, administrators can 'telnet' to the intended destination device and run CDP command.

24.0 Core Dump:

Core dump is the memory image of a router. It is useful to obtain the core dump of a router to find the reason for a router crash. Two most widely used means of configuring core dumps are:

1. By using of TFTP - Trivial File Transfer Protocol
TFTP dumps are usually limited to 16MB. The command used to configure a router to use TFTP for core dump:
exception dump <ip-address>

2. By use of FTP - File Transfer Protocol
To configure a router for core dump using FTP required more configuration steps as below:
step1: ip ftp usename <username>
step2: ip ftp password <password>
step3: exception protocol ftp
step4: exception dump <ip-address>

You can test the core dump by issuing the command 'write core' in privileged exec mode (enable mode). This command will cause a crash, and the content of the memory will be dumped according to the configured setup.

25.0 SPAN monitoring:

The following two commands are useful for setting up a span port and verifying the span port configuration.
1. Set span - This command sets a port or vlan to be monitored.
Ex: set span 5 3/8 both
In the above command, vlan 5 is monitored by port 3/8. The argument 'both' enables monitoring in both the directions.
Ex2: set span 3/7 3/8 both
In the above command, port 3/7 is monitored by port 3/8 in both the directions (both transmit/receive traffic).

2. Show span
This command displays the span configuration. The command 'show trunk [slot-number/ port-number]' on a Catalyst switch displays the vlan information corresponding to that port. You can also use 'show vlan' command to display the vlan information on a port. This is useful in troubleshooting a vlan and allows us to ensure that the ports are configured for intended vlans.

Exam Notes

26.0 Catalyst 5000:

In Catalyst 5000 switches, the top slot (Slot 1) is always populated with supervisor engine. The remaining slots can be populated with interface modules. Failure to load the supervisor module in slot 1 will result in boot failure of the Catalyst switch.

27.0 Frame Relay :

The following three LMI (Local Management Interface) type are supported by Cisco:

1. Cisco (default)
2. ANSI
3. Q933a

Note that, the LMI type must match on either end of the link. That is on the DTE and DCE ends.
The command 'frame-relay lmi-type {ansi|cisco|q933a} is used for assigning a specific lmi to an interface.

Important 'show' commands used in troubleshooting Frame-Relay networks are given below:

1. Show interfaces serial - The information provided by this command include:
- LMI type (cisco/q933a/ansi
- LMI DLCI, Keepalives, Network address and subnet mask.
- Shows the interface and line protocol conditions (Normally interface up, line protocol up)

2. Show frame-relay lmi - Provides LMI statistics.

3. Show frame-relay map: This command shows the configured dlci and ip address mapping.

4. Show frame-relay pvc: This command shows the LMI status of each configured DLCI. The packet stats for input pkts, output pkts, BECN, FECN, DE packet stats are also given.

Acronyms:

-          DSL stands for Digital Subscriber Line

-          DHCP stands for Dynamic Host Configuration Protocol

-          PPP stands for Point to point protocol

-          HTTP stands for Hyper Text Transfer Protocol

-          WWW stands for World Wide Web

-          HTML stands for Hyper Text Markup Language

-          PPTP stands for Point to Point Tunneling Protocol

-          L2F stands for Layer 2 Forwarding

-          L2TP stands for Layer 2 Tunneling Protocol

-          MIME stands for Multipurpose Internet Mail Extensions.

-          CA stands for Certificate Authority.

-          DLL stands for Dynamic Link Labrary

-          ODBC stands for Open Data Base Connectivity.

-          VRML stands for Virtual Reality Modeling Language

-          PEG stands for Joint Photographic Expers Group.

-          PNG stands for portable Network Graphics

-          TIFF stands for Tag image File Format

-          MPEG stands for Moving Pictures Experts Group

-          PDF stands for Portable Document Format.

-          AVI stands for Audio Video Interleaved.

-          PKI stands for Public Key infrastructure.

1. Internetwork IP addressing:

IP addresses are written using decimal numbers separated by decimal points. This is called dotted decimal notation of expressing IP addresses.

The different classes of IP addresses is as below:

Class Format Leading Bit    pattern Network address Range Maximum networks Maximum hosts/ nodes

A N.H.H.H   0 0-126 127 16,777,214

B N.N.H.H 10 128-191 16,384    65,534

C N.N.N.H 110 192-223     2,097,152   254

N: Network address part

H: Host address part

- Network address of all zeros means "This network or segment".

- Network address of all 1s means " all networks", same as hexadecimal of all Fs.

- Network number 127 is reserved for loop-back tests.

- Host (Node) address of all zeros mean "This Host (Node)".

-          Host (Node) address of all 1s mean "all Hosts (Nodes) " on the specified network.

-          The range of numbers from 224.0.0.0 to 239.255.255.255 is used for multicast packets. This is known as Class D address range.

-          The default subnet mask for

o        Class A network: 255.0.0.0

o        Class B network: 255.255.0.0

o        Class C network: 255.255.255.0

2. TCP/IP protocol suite was initially developed based on Unix operating system and it is native to Unix. TCP/IP protocol suite was added to other operating systems like Windows later.

3. ATM:

-          ATM, Asynchronous Transfer Mode, uses 53 byte cells for all transmissions All cells are 53 byte long and consist of a 5 byte header and 48 bytes of data.

4. T1,T2, and T3 connections:

-          The speeds of the Tx connections are as given below:

o        T1: 1.544 MBPS consisting of 24 channels of 64 kBPS

o        T2: 6.312 MBPS consisting of 96 channels of 64 kBPS

o        T3: 43 MBPS consisting of 672 channels of 64 KBPS

5. DSL:

-          DSL uses existing copper phone lines. The access speeds can be up to 9 MBPS. but has distance limitations and available in only certain exchange areas.

-          There are several categories of DSL:

o        Asymmetric DSL (ADSL): Here data flow is asymmetric. Data flow in one direction is different from that in the other direction.

o        Symmetric DSL (SDSL): Here the data flow is symmetric, that the data flows equally in both directions.

o        Other not so much used or known types of DSL are BDSL, HDSL, and VDSL.

6. The range of numbers from 224.0.0.0 to 239.255.255.255 is used for multicast packets. This is known as Class D address range.

7. Telnet, FTP, and TFTP:

-          TCP/IP is the protocol used when you are Telnetting to a remote host. Telnet is used for terminal emulation that runs programs remotely.

-          FTP is used to transfer files. FTP is a connection-oriented protocol. It uses TCP/IP for file transfer.

-          TFTP (Trivial File Transfer Protocol) uses UDP. TFTP is a connectionless protocol.

8. A valid IP address on a host / node can't start with 127; 127.X.X.X is reserved for local loop back. A valid IP address can't be larger than 255 (in any octet), The maximum allowed value is 255 in any or combination of octets. For example, 150.206.256.31 is an invalid IP, since one octet exceeded the value 255. An example of valid IP is 202.122.154.11.

9. Tracert, Ping use ICMP as their base protocol. ICMP messages are carried in IP data grams.

10. SMTP is used to upload mail to the mail server. POP3 is used for downloading mail from a mail server to a client machine running POP3 client.

11. A firewall is a security mechanism, which prevents unauthorized access to a network or a resource on a network.

12. Important port numbers:

The port numbers used by different programs are as below:

-          FTP: Port #21

-          Telnet: Port #23

-          SMTP: Port #25

-          SNMP: Port #161

-          WWW: port 80,

-          NNTP: port 119,

-          POP: port 110.

It is also important to know that FTP, Telnet, SMTP use TCP; whereas TFTP, SNMP use UDP.

13. Repeaters, Bridges, and Routers:

-          Repeaters work at Physical layer (Layer 1),

-          Bridges and simple switches work at Data Link Layer (Layer 2),

-          Routers work at Network Layer (Layer 3) of ISO Reference Model.

14. Gateway is used to translate protocols, as it works at application layer.

15. Telnet requires an username and password to access.

16. ISDN:

-          ISDN specifies two standard access methods:

-          BRI (Basic Rate Interface):

o        Consists of two B channels (64Kbps) and one D channel (16Kbps).

o        The B channels can be used for digitized speech transmission or for relatively high-speed data transport.

o        The D channel carries signaling information (call setup) to control calls on B channels.

-          PRI (Primary Rate Interface):

o        Consists of 23 B channels and one D channel with a bandwidth of 1.544Mbps.

o        PRI uses a DSU/CSU for a T1 connection. B stands for Bearer Channel.

17. TCP/IP port assignments used in the Internet: Originating source port numbers are dynamically assigned by source host, and usually greater than 1023. The following are the recommended port numbers:

-          Numbers 0 - 255 are used for public applications

-          Numbers 255 - 1023 are assigned to companies so that they can use these port numbers in their applications.

-          Numbers above 1023 are used by upper layers to set up sessions with other hosts and by TCP to use as source and destination addresses.

18. Some of the important commands useful in trouble shooting TCP/IP networks:

I.                   Ipconfig: Displays TCP/IP configuration values, including IP address, subnet mask, and default gateway.

II.                Ping: This command can be used to verify whether the target ip address or host name is present. You need to specify the target IP address or host name.

III.              Route: Displays and manipulates route information.

IV.              Tracert: Determines the route packets take to reach the specified destination.

19. HTTP is the protocol used for accessing the World Wide Web services. HTTP operates over TCP/IP. TCP/IP is the protocol, which is used by all internet applications such as WWW, FTP, Telnet etc.   IPX/SPX is proprietary protocol stack of Novell NetWare.

20. TCP is a full-duplex, connection-oriented protocol. It incorporates error checking as well. UDP (User Data gram Protocol): UDP is a thin protocol. UDP is a connectionless protocol. It doesn't contact the destination before sending the packet and doesn't care whether the packet is reached at the destination. UDP uses port number 6.

22. The core administrative unit in DNS is called "zone". A zone is a physical file composed of resource records that define a group of domains. A domain is a node in the DNS namespace and all sub-domains below it.

23. Telnet is used for terminal emulation that runs programs remotely.

FTP is used to transfer files.

24. To see TCP/IP configuration on a Windows 95 / 98 computer in a graphical format, use WINIPCFG. It will display your IP address, subnet mask, default gateway, hardware MAC address and other details.

To see TCP/IP configuration in a non-graphical format or on an NT machine, use IPCONFIG. It will also display the IP configuration information on an NT machine. To get more details, use IPCONFIG/ALL.

25. A valid IP address on a host / node can't start with 127; 127.X.X.X is reserved for local loop back. A valid IP address can't be larger than 255 (in any octet), The maximum allowed value is 255 in any or combination of octets. For example, 150.206.256.31 is an invalid IP, since one octet exceeded the value 255. An example of valid IP is 202.122.154.11.

26. TCP/IP utilities:

-  NBTSTAT This utility displays current NetBIOS over TCP/IP connections, and display NetBIOS name cache.

-  NETSTAT Displays protocol statistics and current TCP/IP connections since the server was last booted.

-  TRACERT This command is used to determine which route a packet takes to reach its destination from source.

-  IPCONFIG Displays Windows IP configuration information.

-  NSLOOKUP This utility enables users to interact with a DNS server and display resource records.

-  ROUTE This command can be used to display and edit static routing tables.

27. PAP and CHAP:

-  PAP uses 2-way handshaking. Passwords are sent in clear text across the link. Therefore, PAP is to be used only when it not possible to use CHAP.

-  CHAP uses 3-way handshaking. CHAP uses Challenge/ Response method that provides protection against the password capture while authenticating the user. One should use CHAP whenever it is possible.

28. HOSTS file:

-  HOSTS file is an ASCII file and can be edited using Notepad or any other text editor. The IP address and domain name ns.dname.com of a proper entry in a HOSTS file looks like: 196.54.202.16 ns.dname.com. Hash mark (#) is used before writing the comment in HOSTS file. The entire line after the # mark is treated as comment. You can enter any number of lines into a HOSTS file. But the number of characters that each line in a HOSTS file is limited to 255.

29. PPP&SLIP:

-  PPP offers multi protocol support, error correction and compression.

-  Multilink PPP allows multiple physical links be used to transfer information. The data passing through different physical connections form a single logical stream of data, thus increasing the effective bandwidth.

-  PPP supports Password Authentication Protocol (PAP) and, Challenge Handshake Authentication Protocol (CHAP).

-  SLIP is an older protocol and supports only TCP/IP. No error correction/ compression are offered by SLIP.

30. Some frequently occurring HTTP error messages:

1.  Client side:

-  404-not found (specified file not found on server side)

-  401 - unauthorized

2.  Server side:

-  500 - internal server error

-  502 - Server overloaded

-  503 - service unavailable

-  504 - gateway timeout

31. OSI 7 layers: The 7 layers of OSI model are:

1.  The Application Layer: Application layer is responsible for identifying and establishing the availability of intended communication partner and verifying sufficient resources exist for communication. Some of the important application layer protocols are: WWW, SMTP, FTP, etc.

2.  The Presentation Layer: This layer is responsible for presenting the data in standard formats. This layer is responsible for data compression, decompression, encryption, and decryption. Some Presentation Layer standards are: JPEG, MPEG, MIDI, PICT, Quick Time, TIFF.

3.  The Session Layer: Session Layer is responsible for co-coordinating communication between systems/nodes. The following are some of the session layer protocols and interfaces: a) Network File System (NFS),SQL,RPC (Remote Procedure Call), X-Windows, ASP, DNA SCP.

4.  The Transport Layer: The Transport Layer is responsible for multiplexing upper-layer applications, session establishment, and tearing-down of virtual circuits. This layer does "flow control" to maintain data integrity. Flow Control prevents the problem of a sending host on one side of the connection overflowing the buffers in the receiving host.

5.  The Network Layer: There can be several paths to send a packet from a given source to a destination. The primary responsibility of Network layer is to send packets from the source network to the destination network using pre-determined methods. Routers work at Network layer.

6.  The Data Link Layer:

-  Data Link Layer is layer 2 of OSI reference model. This layer is divided into two sub-layers:

A.  Logical Link Control (LLC) sub-layer.

B.  Media Access Control (MAC) sub-layer.

-  The LLC sub-layer handles error control, flow control, framing, and MAC sub-layer addressing.

-  The MAC sub-layer is the lower of the two sub-layers of the Data Link layer. MAC sub-layer handles access to shared media, such a Token passing or Ethernet.

7.  Physical Layer: The actual flow of bits takes place through Physical layer. At Physical layer, the interface between the DTE and DCE is determined. The following are some of the standard interfaces are defined at Physical layer: A> EIA/TIA-232, EIA/TIA-449, V.24, V.35, X.21, G.703, HSSI (High Speed Serial Interface).

32. FTP utility is used for transferring files between server and client. It uses TCP/IP protocol and therefore connection oriented. The ftp is a reliable (since it is connection oriented) method of data transmission.

The syntax of ftp is as below:

ftp [-v] [-n] [-I] [-d] [-g] [-s:filename] [host name].

Where,

-v Suppresses any display of server responses (verbose)

-n Prevents automatic logon when the connection with the server has been established.

-I Turns off interactive prompting during file transfers

-d Displays all ftp commands exchanged between client and server. Useful during debugging.

-g Prevents the use of wildcard characters in path and file names.

-s: filename : Specifies a text file containing ftp commands and then runs the commands within the file. This is similar to running batch file in DOS.

Hostname Specifies the host to connect to and must be the last parameter to be specified.

FTP commands:

-  To upload a single file using FTP, use the command "put",

-  To download a single file using FTP, use the command "get",

-  To upload multiple files using FTP, use the command "mput",

-  To download multiple files using FTP, use the command "mget".

33. Search Engines:

-  By placing the phrase in double quotes, the search engine returns all the pages that contain the phrase. For example, to return all pages with the phrase ‘space ship’ type in the same within double quotes “space ship”; On the other hand +space +ship return all pages that contain 'space' and 'ship' not necessarily together.

34. A computer on Internet having a unique IP address is known as HOST.

35. PPTP, L2TP, and L2F:

-  PPTP: PPTP is Microsoft proprietary protocol and widely supported. PPTP supports wide range of protocols such as TCP, NetBEUI, IPX.

-  L2F: It was developed by Cisco systems and is proprietary protocol. L2F uses UDP instead of TCP for forwarding the packets through the tunnel.

-  L2TP: L2TP uses IPSec for encryption.

36. A DNS zone file contains the resource records for the part of the domain for which the zone is responsible. Some of the resource records are:

1.  SOA (Start Of Authority Record): The first record in any zone file is the SOA record. The SOA file contains some general parameters such as contact e-mail of the person responsible for this zone file, the host on which zone file is maintained etc.

2.  The NS Record (Name Server Record): NS Record contains the name servers for this domain. This will enable other name servers to look up names in your domain.

3.  MX Record (Mail Exchange Record): MX record tells us which host processes mail for this domain.

4.  Host Record (A Record): A host record is used to statically associate hosts names to IP addresses within a zone. The syntax for this is

5.  <hostname> IN A <ip address of the host>

ex:

NameServer1 IN A 196.52.34.143

-  Here 'NameServer1' is the host name and 196.52.34.143 is its ip address.

6.  CNAME Record (Canonical name): These records allow you to use more than one name to point to a single Host. Using CNAME, you can host both WWW and FTP servers on the same machine.

7.  Reverse Look up is useful when you want to implement security. Reverse look up ensures that the domain name is indeed the domain that it claims to be.

The correct format for Pointer record is

ex.: 16.12.54.204.in-addr.arpa. IN PTR services.yourcompany.com

Here the IP numbers are written in backward order and in-addr.arpa is appended to the end, creating a Pointer record.

37. ARP, RARP, and BootP:

-  Since IP address is a logical address, if a packet is to be delivered to another machine, its physical address (MAC address) needs to be known. Address Resolution Protocol (ARP) is used to resolve or map a known IP address to a MAC sub-layer address to allow communication on a multi-layer access network such as the Internet.

-  Reverse ARP (RARP) is used to obtain an IP address using an RARP broadcast. RARP is used to obtain IP address from a known MAC address.

-  BootP (Bootstrap Protocol): When a diskless workstation is powered on, it broadcasts a BootP request on the network. A BootP server responds with its IP address, Default gateway, etc.

38. Proxy Server:

A Proxy server is primarily used in between the Web and the client machines that reside on a LAN / intranet. It serves multiple fuctions as required, including:

1.  It receives the client requests for Web pages and forward the requests if necessary. If the pages are available in its cache (Don’t confuse with L1/L2 cache of CPUs!), it immediately serves the pages to the clients. This improves response times and efficient bandwidth utilization.

2.  A proxy server maps the IP addresses of the clients to one or more IP addresses for accessing the Internet. This way, a Proxy can be used to save precious IP addresses available on the Internet. At least, one valid IP address is required to access the Internet for multiple clients, that are connected to the Internet through Proxy.

3.  A Proxy Server can also be used to secure the clients from possible security threats from the Internet by configuring appropriately. This improves the safety of the client machines malicious attacks.

39. Cookies:

-  A cookie is a plain text file that sends out client information to the corresponding Web server, usually when the client makes a visit to the Web server. Disabling Cookies may result in improperly loaded Web pages.

40. A multi-homed computer will have atleast two IP addresses defined. These IP addresses can be defined to a single network card or there might be more than one network card with atleast one IP address defined to each. It is important to note that there can be more than one IP address defined to a single network card.

41. Only WINS update entries dynamically. All others require records to be entered manually. Remember that DNS and HOSTS resolve FQDN names to IP addresses, whereas, LMHOSTS and WINS resolve NetBIOS names to IP addresses.

42. Browsers:

-  Configuring the browser not to show pictures enable the Web pages to load faster.

-  A correctly formatted connection to access a Web site over a secure link will have "https://".

43. News Service:

-  By installing Internet News service, you can enable all group members to exchange threaded messages.

-  NNTP is a service. Users can connect to NNTP service using client software like Microsoft Internet Mail and News through TCP/IP.

44. The port number needs to be specified if you are accessing a website at a port other than the default port, the default port number for WWW traffic is port 80. By default, the Web page request is sent to port 80 unless otherwise specified. For example, if you want to access a web page at port number 5064, the correctly formatted URL is http://www.yoursite.com:5064/default.htm.

45. MIME specifies how non-ASCII (binary) messages such as graphics can be sent across the Internet.

46. Features supported by HTTP1.1:

1.  Host headers enable a single IP address to be assigned to multiple web sites.

2.  Persistent connections allow a single session between a client and server to transfer multiple objects, connected to a single resource.

3.  Pipelining does not require clients to wait for a confirmation or completion of each request before sending another request.

Older browsers support only HTTP version 1.0, whereas most of the modern browsers support HTTP ver.1.1

47. Server Side Includes (SSI):

Server-side include (SSI) directives instruct the Web server to insert the contents of another file into an HTML page. This is a convenient way to store information used on many pages in a single file.

48. When you enable SSL communication on your Web site, you need to install a digitally certified key on your Web server.

49. At least first and second level domain names (in this case company.com) are to be registered with InterNIC for access over Internet. Third level and below can be resolved by installing DNS server.

50. FTP site can usually be configured with the following messages. Users (clients computers) get these messages when appropriate.

1.  Welcome message: When a user enters an FTP site, this message is displayed.

2.  Exit message: When a user exits an FTP site, this message is displayed.

3.  Maximum connections: This is displayed when the maximum simultaneous connections limit is reached at the FTP server, and the user computer can not be connected because of this.

51. Certificate authority (CA) is any trusted third party that issues certificates and verifies the identity of a server or an individual for security purposes. A certificate is a digital signature containing the identity of a server or an individual.

52. Active Server Pages (ASP):

-  ASP tags begin with "<%" and end with "%>". The tags are known as delimiters.

-  ASP runs at the server side.

-

53. JScript, VBScript, and Java are some of the client side content tools that run on the client computers.

54. URL (Uniform Resource Locator):

A URL uniquely identifies the location of a computer, directory, or file on the Internet. The URL also specifies the appropriate port to be used (if different from default port value), Internet protocol, such as HTTP or FTP. The following is an example of a correctly formed URL: http://www.microsoft.com. When no file is specified in the URL, the default.htm or default.asp file, located in the home directory of the Web site is displayed by the client's browser.

55. File Extensions:

The extensions that are usually associated with some important file types are:

1.  Active Server Pages -- .asp

2.  Java source code -- .java

3.  Java Script -- .js

4.  Perl script -- .pl

56. CGI and ISAPI can only be used for server side scripting.

VBScript, JavaScript, ASP are used for client side scripting.

57. XML (Extensible Markup Language) is a reduced version of SGML.

58. A DLL is used in Microsoft operating systems. DLLs' are library routines that are called to perform some common tasks within Microsoft operating environment. DLLs can also be developed by third party vendors to enable integration of their programs into Microsoft environment. Multiple programs can call a DLL.

59. If you want to embed a Pert script into html page, the correct syntax for inserting PerlScript is

Note that "/" is placed before the SCRIPT command as shown, to signify that it is the end of the script.

60. The correct syntax for inserting Java Script into html page is

Note that "/" is placed before the SCRIPT command as shown, to signify that it is the end of the script.

61. ODBC is Microsoft's implementation for accessing Microsoft SQL Server / Access databases from a Web Server, and delivering the results over the Web in html format to client computers.

62. The correct sequence of tags in an html page is:

<html>

<head>

<title>

</title>

</head>

<body>

</body>

</html>

Please note that the tag "title" comes between "head" tags. "title" describes the title of the page and usually appears in the Title window of the browser.

63. Correct syntax to insert a comment into html page is:

The correct syntax is

An example is

Here 'BEGIN FASTCOUNTER LINK' is the comment that you have inserted into html code.

64. HTML:

-  If you write <IMG SRC="myimage.gif">, the web server assumes that the image is in the same folder as that of the web page. If the image is in different folder, you need to specify the folder in the IMG directive ex: <IMG SRC="images/myimage.gif">.

-  Correct syntax to insert a hyperlink to www.yahoo.com, when user clicks on "YAHOO" is <A HREF="http://www.yahoo.com">YAHOO</A>

-  To include special characters, such as '<', '>' etc. we can use specified character entities.

This is required because, these characters have special meaning within html and therefore need to be specified otherwise.

Given below are some character entities used in HTML:

Less than (<): <

Greater than (>): >

Registered trademark: ®

-  The attribute "ALT" provides an alternative description of an image. This is useful, for example if a client has selected "Text Only" version and prevented any images to be down loaded for faster access to a web page. Also, it may so happen that a browser does not support the image format and can not display the image.

Common sytax for displaying alternate text is:

65. Some of the image / video / audio file formats available are:

1.  GIF (extension .gif): GIF is one of the most widely used formats for images on the World Wide Web. GIF images are very compact and have only 256 colours or 8 bit.

2.  JPEG (Joint Photographic Expert Group, extension .jpg): JPEG is a 24 bit, 16-million colour graphic file format widely used on the Web. JPEG uses compression to reduce the file size and recommended for continuous tone images.

3.  PNG (Portable network Graphics, extension .png): This is a new format, not yet widespread. Specifically designed for the Web.

4.  MOV( Quick Time Movie, extension .mov): Quick Time Plug-in is required to play .mov files on the Internet.

5.  MPEG (Extension .mpg): MPEG can provide full motion, full screen video with special software /or hardware.

6.  PDF (Extension .pdf): This format is developed by Adobe Acrobat. It is used to display documents that are created using Adobe Acrobat. .pdf format is most widely used over the Internet to distribute the documents.

66. Web Graphics:

-  VRML allows the display of 3D pictures with Web browsers.

-  All .bmp,.gif, and .jpeg use raster graphics, where as Flash uses vector graphics. Vector graphics take less file space compared to raster graphics.

-  VRML files use the extension .wrl.

67. A text editor such as Note pad can be used for writing HTML pages. But you need to enter all the code yourself (including html tags). On the other hand, if you are using a GUI editor to write HTML pages, inherent tags are inserted by the editor itself, such that you don't have to worry about the syntax. This will save time more efficient.

68. A Web page written in HTML can usually support the following lists:

1.  Unordered lists:Unordered lists are bulleted and used when it is not required to number the lists.

2.  Ordered lists: In an ordered list, the number precedes each list item.

3.  Definition lists: A definition list typically lists each definition term followed by an indented description.

The correct syntax for writing Ordered lists is:

<OL>

<L1>Bulleted item 1

<L2>Bulleted item 2

</OL>

Note that there is no /L1 or /L2 tag.

The correct syntax for writing Unordered lists is:

<UL>

<L1>Bulleted item 1

<L2>Bulleted item 2

</UL>

Note that there is no /L1 or /L2 tag.

The correct syntax for writing Definition Lists is:<DL>

<DT> Definition Term 1

<DD> Definition Description 1

<DT> Definition Term 2

<DD> Definition Description 2

/DL

Remember that CompTIA expects you to be familiar with HTML tags and writing Web pages with pure HTML.

69. Flash: Flash is from Macromedia. Flash is based on vector graphics, and used for developing dazzling Web sites. You can also incorporate animation with Flash. Flash plug-in is required to display Flash content.

Shockwave: Shockwave is also from Macromedia. Shockwave is used for displaying interactive Web sites involving video, graphics, and Audio. Shockwave plug-in is required to display web pages with Shockwave content.

70. The correct syntax of html code to start an email client on client browser is

<A HREF="mailto:support@yahoo.com"> Email Yahoo Support </A>

This command will open the clients email program and puts "support@yahoo.com" in the "TO" address field. support@yahoo.com is taken only as an example.

71. A trademark is an original and unique name or symbol that is provided legal protection indefinitely.

72. A copyright applies to orignal works of "authorship". It is protected for the life of the author and an additional 50 years.

73. There are some occasions, where it will not constitute violation of copyright law:

1.  Parody

2.  Use by free educational institutions, where in portions of the material is used for non-profit

3.  Limited use, wherein, the material is used only to quote some portions.

4.  Archiving purposes.

74. The following are valid representations of copyright display:

75. SSL, Secure Socket Layer, works by using a private key to encrypt data that's transferred over the SSL connection. Both Netscape Navigator and Internet Explorer support SSL, and many Web sites use the protocol to obtain confidential user information, such as credit card numbers. By convention, Web pages that require an SSL connection start with https: instead of http:.

Another protocol for transmitting data securely over the World Wide Web is Secure HTTP (S-HTTP). Whereas SSL creates a secure connection between a client and a server, over which any amount of data can be sent securely, S-HTTP is designed to transmit individual messages securely. SSL and S-HTTP, therefore, can be seen as complementary rather than competing technologies. Both protocols have been approved by the Internet Engineering Task Force (IETF) as a standard.

76. When using "PUSH" technology, the server pushes the information to the browser, even if the browser doesn't request that information. This is different from PULL technology, wherein browser requests the information or pulls the information from the server.

77. X.509 is the most widely used standard for defining digital certificates.

78. S/MIME, Short for Secure/MIME, a new version of the MIME protocol that supports encryption of messages. S/MIME is based on RSA's public-key encryption technology.

http://www.broadband-forum.org/technical/trlist.php   
      
      
http://wiki.broadbandforum.in/bsnl-broadband

http://www.brouckie.be/cgi-bin/IPsubnetting/index.pl

Standard	Compliance
802.3	standard for 10BaseT Ethernet CSMA/CD
802.3u	IEEE standard for 100BaseT (Fast Ethernet) incorporating CSMA/CD protocol.
802.3z	IEEE standard for Gigabit Ethernet
802.5	IEEE standard for Token Ring networks
802.11	IEEE standard for wireless LAN

Command	Description
PING	Used to ping the remote system (or the local host) to see that the TCP/IP connection is through.
NBTSTAT	This utility displays current NetBIOS over TCP/IP connections, and display NetBIOS name cache.
NETSTAT	Displays protocol statistics and current TCP/IP connections since the server was last booted.
TRACERT	Used to determine which route a packet takes to reach its destination from source.
IPCONFIG	Used to display Windows IP configuration information.
NSLOOKUP	This utility enables users to interact with a DNS server and display resource records.
ROUTE	Used to display and edit static routing tables.