Computer Networking Concepts

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Questions and Answers

Give one difference between Multicasting and Broadcasting.

Multicasting sends packets to a specific group of recipients, while broadcasting sends packets to all recipients on a network.

What is the full form of WAN?

Wide Area Network

What is Bit Rate?

Bit Rate is the number of bits transmitted per second.

Differentiate between Half duplex and Full Duplex.

In Half Duplex, communication is bi-directional, but only one party can transmit at a time, whereas in Full Duplex, both parties can transmit simultaneously. Signup and view all the answers

Show the Amplitude and wavelength in an analog signal.

Amplitude is the height of the wave from the center line. Wavelength is the distance between two consecutive peaks or troughs. Signup and view all the answers

What is piggybacking?

Piggybacking is a technique where acknowledgments are attached to outgoing data frames, reducing the number of frames transmitted. Signup and view all the answers

What is the full form of CSMA/CA?

Carrier Sense Multiple Access with Collision Avoidance Signup and view all the answers

Draw and explain the scenario of delayed duplication and retransmission in stop-and-wait protocol for noisy channel.

In a noisy channel, a transmitted frame may be lost or corrupted. The sender waits for an acknowledgment (ACK) but if it doesn't receive one within a timeout period, it retransmits the frame. If the original frame was received but the ACK was lost, the receiver gets a duplicate. The receiver needs to detect and discard this duplicate using sequence numbers. Signup and view all the answers

Consider a noiseless channel with a bandwidth of 3000 Hz transmitting a signal with two signal levels. What can be the maximum bit rate?

Maximum bit rate = 2 * Bandwidth = 2 * 3000 Hz = 6000 bps. Signup and view all the answers

What is framing? Why is framing required? Explain any one method with example.

Framing is the process of dividing a continuous stream of bits into manageable blocks, called frames. Framing is required because the physical layer transmits a continuous stream of bits, and the data link layer needs to organize these bits into meaningful data units. One method is character count, where the first byte indicates the number of bytes in the frame. Signup and view all the answers

Explain Non persistent, 1-persistent and P-persistent CSMA protocol.

Non-persistent CSMA: Listens to the channel; if busy, waits a random time before listening again. 1-persistent CSMA: Listens to the channel; if busy, continuously listens until it is free and then transmits immediately. P-persistent CSMA: Listens to the channel; if busy, waits until it is free. Then transmits with probability p, or defers with probability 1-p. Signup and view all the answers

Explain hidden station and exposed station problem in wireless network in detail.

Hidden station: Station A can communicate with B, and Station C can communicate with B, but A cannot hear C. Thus, A and C might transmit at the same time, causing a collision at B. Exposed station: Station B is transmitting to A, and C wants to transmit to D. Because C hears B's transmission, C incorrectly assumes it cannot transmit to D, even though the transmission to D would not interfere with B's transmission to A. Signup and view all the answers

Draw and explain IEEE 802.3 (Ethernet) frame structure.

The IEEE 802.3 frame structure consists of Preamble, Start Frame Delimiter (SFD), Destination Address, Source Address, Length/Type, Data, and Frame Check Sequence (FCS). Signup and view all the answers

Calculate CRC for the data 10101010 and the generator polynomial is x^2 + x.

Given data: 10101010. Generator polynomial: x^2 + x which is 110 in binary. Append two zeros to the data: 1010101000. Divide 1010101000 by 110 using binary long division. The remainder is 01, so the CRC is 01. Signup and view all the answers

What is hamming code? Calculate hamming code for the message 11010100.

Hamming code is an error-correcting code that can detect and correct single-bit errors. To calculate the Hamming code for 11010100, determine the positions for parity bits (powers of 2), calculate parity bits, and insert them into the message. Result: 10110101010. Signup and view all the answers

Explain parity check mechanism with its advantages and limitations. Take suitable example for explanation.

Parity check adds a single bit to ensure that the number of 1s in a byte is either even (even parity) or odd (odd parity). Advantage: Simple to implement. Limitation: Can only detect odd number of bit errors. Example: If data is 1100101, even parity bit is 0 (total 4 ones). Signup and view all the answers

Draw the link state packet and state the significance of Age field in Link state packet. Also explain the flooding mechanism used in link state routing algorithm.

The link state packet (LSP) contains information about a router's neighbors. The Age field indicates the remaining validity of the LSP. Flooding involves a router sending its LSP to all its neighbors, who then forward it to their neighbors, ensuring all routers have the network topology. Signup and view all the answers

Explain distance vector routing algorithm. Give example and justify why the count-to-infinity problem occurs?

Distance vector routing involves each router sharing its routing table with its neighbors. Count-to-infinity occurs when a link fails, and routers repeatedly update their distances based on incorrect information from neighbors, leading to an infinite loop. For example, if A is connected to B with cost 1, and B is connected to C with cost 1, and the link between B and C fails, A might increase the cost to reach C to infinity, but B, still believing it can reach C, will repeatedly increment the cost, leading to inaccurate routing information. Signup and view all the answers

Explain how congestion is managed in virtual circuit and datagram subnet?

In virtual circuit subnet, congestion is managed using techniques like traffic shaping and admission control to reserve resources. In datagram subnet, congestion is managed using techniques like congestion control algorithms (e.g., TCP congestion control) and routing algorithms to avoid congested links. Signup and view all the answers

Explain working of Dijkstra's shortest path algorithm with example.

Dijkstra's algorithm finds the shortest path from a source node to all other nodes in a graph. It maintains a set of visited nodes and a set of unvisited nodes, iteratively selecting the unvisited node with the smallest distance from the source and updating the distances to its neighbors. Suppose we have nodes A, B, and C, with costs A->B=1 and B->C=1. Starting from A, Dijkstra's algorithm finds the shortest path to B (cost 1) and then to C (cost 2). Signup and view all the answers

Explain SMTP with MIME type.

SMTP (Simple Mail Transfer Protocol) is used to send email messages. MIME (Multipurpose Internet Mail Extensions) extends SMTP to support multimedia content, such as images, audio, and attachments, by defining the format of the email message. Signup and view all the answers

What is three-way handshake? Explain how three-way handshake solves delayed duplicate problem.

The three-way handshake is used to establish a TCP connection: SYN, SYN-ACK, ACK. The sequence numbers in the TCP headers ensure that delayed or duplicate packets from previous connections are discarded, which helps to solve delayed duplicate problems. Signup and view all the answers

Explain Domain Name System (DNS) with the importance of resource record. Explain any four resource records.

DNS translates domain names (e.g., google.com) to IP addresses, enabling users to access websites using human-readable names. Resource records (RRs) contain information about domain names. Four types: A (maps hostname to IPv4 address), AAAA (maps hostname to IPv6 address), MX (specifies mail server), NS (specifies name servers). Signup and view all the answers

What are the duties of transport layer? Compare those with that of data link layer.

Transport layer duties include reliable data transfer, flow control, and congestion control. The data link layer handles framing, error detection, and media access control within a local network. Transport layer ensures end-to-end communication, while the data link layer ensures node-to-node communication. Signup and view all the answers

Flashcards

Broadcasting

Sending to all; one sends, all receive.

Multicasting

Sending to a specific group; one sends, group receives.