Computer Networks

Hub is a Physical layer devices that are really just multiple port repeaters. When an electronic digitalsignal is received on a port, the signal is reamplified or regenerated and forwarded out allsegments except the segment from which the signal was received. switch

(1) In networking, a device responsible for multiple functions such as filtering, flooding,and sending frames. It works using the destination address of individual frames. Switches operateat the Data Link layer of the OSI model.

(2) Broadly, any electronic/mechanical device allowingconnections to be established as needed and terminated if no longer necessary.

That is a TCP ip rule you can't ping to another subnet why because of if you try to communicate to another machine the machine's TCP/IP protocol suite will check by using AND ing the destination IP. Iif it doesn't mach the subnet it will send that request to the gateway so the responsibility goes to gateway to reach the other network may be the gateway is not configure correctly

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft and IBM for the use on small subnets.

10Base2

—An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling, with a contiguous cable segment length of 100 meters and a maximum of 2 segments.

10Base5

—An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling, with 5 continuous segments not exceeding 100 meters per segment.

10BaseT

—An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling and twisted pair cabling.

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X"

Server-based networkPeer-to-peer networkPeer-to-peer network, computers can act as both servers sharing resources and as clients using the resources.Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration

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ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

As Saurabh said; we can use static and Dynamic Routing in one network. However Dyanmic Routing is used to have the best path no matter what the status of the physical links.All routing protocols have some sort of shortest-path or lowest-cost or best-choice algorithm to help you weigh all the options available. Static routing can be used in a small network to reduce the work of the network administrator or to use a particular route only to forward the packet; we need static routing.

The three types of routing tables are fixed, dynamic, and fixed central. The fixed table must be manually modified every time there is a change. A dynamic table changes its information based on network traffic, reducing the amount of manual maintenance. A fixed central table lets a manager modify only one table, which is then read by other devices. The fixed central table reduces the need to update each machine's table, as with the fixed table. Usually a dynamic table causes the fewest problems for a network administrator, although the table's contents can change without the administrator being aware of the change.

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.

When hierarchical routing is used, the routers are divided into what we call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.