Computer Networks

This is using different network build purpose, so connect first router to first switch and connect 10 nodes with first switch, this is one network ex:192.168.1.0 networkand connect second router to second switch with 10 nodes this is another network ex:192.168.2.0 network the same method third router, fourth router ,third switch and fourth switch ex:192.168.3.0 network and 192.168.4.0 network now u connect all networks in one segment thats all.

A switch can have an Ip address for telnetting purpose.So, if you telnet to the switch, and if you have no password on Telnet you can access the switch (provided that there is no privileged mode password set) and then 'Show Run' , you can read the running configuration.

Piggybacking is gaining access to restricted communication channel by using session that another user has already established. Piggybacking can be defeated by logging off before leaving a workstation or terminal or by initiating a protected mode, such as via a screensaver, that requires re-authentication before access can be resumed.

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The Mount protocol returns a file handle and the name of the file system in which a requested file resides. The message is sent to the client from the server after reception of a client's request.

Interior gateways connect LANs of one organization, whereas exterior gateways connect the organization to the outside world.

A pseudo tty or false terminal enables external machines to connect through Telnet or rlogin. Without a pseudo tty, no connection can take place.

An unspecified passive open has the server waiting for a connection request from a client. A fully specified passive open has the server waiting for a connection from a specific client.

A TCB is a complex data structure that contains a considerable amount of information about each connection.

Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the password usually requesting the user's ID for tracking purposes only. Anonymous FTP is used to enable a large number of users to access files on the host without having to go to the trouble of setting up logins for them all. Anonymous FTP systems usually have strict controls over the areas an anonymous user can access.

Terminal emulation is the ability to make one computer terminal appear like some other terminal.

Terminal emulation is used to give the users the ability to log on and get direct access to legacy programs in a mainframe operating system.The emulation program runs like any other workstation application as a separate program task.

Terminal emulation comes in the application layer.

A virtual channel defines a single point to point connection, identified by its virtual channel identifier.An individual channel can be uniquely identified by its virtual channel and virtual path number. The insertion of VCs enables to implement policies for allocating the physical channel bandwidth, which enables to support quality of service in applications.

Across LANs and WANs.

Beaconing is a process which allows the network to render their network problems by them-selfToken ring and FDDI(Fibre Distributed Data Interface) networks make use of this process.

It is also a signalling error condition in wireless/LAN networks,during a failure the packets are transmitted as beacons,this beacon identifies the neighboring transmission which is active and helps in generation of an auto reconfiguration,hence the node which come under failure domain, automatically initiate a diagnostic measure and try to bypass the failure.

Headers and trailers are the concepts of OSI model.

Headers are information structures which identifies the information that follows, such as a block of bytes in communication.

Trailer is the information which occupies several bytes at the end of the block of the data being transmitted.They contain error-checking data which is useful for confirming the accuracy and status of the transmission.

During communication of data the sender appends the header and passes it to the lower layer while the receiver removes header and passes it to upper layer. Headers are added at layer 6,5,4,3 & 2 while Trailer is added at layer 2.

Within an autonomous system the interior gateway protocol (IGP) is used to exchange routing information.

There are two types of IGP

1.Distance-vector routing protocol

2.Link-state routing protocol.

Using a single IP address and locally splitting it up so that this single network IP address can actually be used on several interconnected local networks is known as netted IP.

A default subnet mask 255.0.0.0 for Class A,

255.255.0.0 for class B,

255.255.255.0 for Class C.