Computer networks multiple choice questions with answers 07

Computer networks multiple choice questions with answers, entrance exam quiz questions on computer networks, solved exam questions on computer networks, MCQ in CN

Computer Networks MCQ - SET 07

1. Key difference between User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) is

(a) TCP is connection-oriented, while UDP is connection-less

(b) UDP is a reliable byte stream protocol, while TCP is not

(c) UDP uses sequence numbers, while TCP does not

(d) UDP enforces flow control, while TCP has no flow control

Click here to view answer and explanation

Ans : (a)

Answer: (a) TCP is connection-oriented, while UDP is connection-less The Transmission Control Protocol (TCP) helps to: ensure the recipient receives all of the data that’s sent (via a delivery receipt), and keep the data transmissions organized by ensuring that packets are received by the recipient in their intended order. Hence, TCP is a connection-oriented communication protocol. On the other hand, User Datagram Protocol (UDP) requires no connection to be established prior to sending your data packets (or, more specifically, datagrams). [Please refer here for more on TCP and UDP]

 

2. How IPv6 is different from IPv4?

(a) Quality of Service is better in IPv4

(b) Expanded IP address space for IPv6

(c) IPv4 is better than IPv6 in terms of support for mobility

(d) None of the above

Click here to view answer and explanation

Ans : (b)

Answer: (b) Expanded IP address space for IPv6 Internet Protocol version 6 (IPv6): IPv4 is based on 32-bit addressing, limiting it to a total of 4.3 billion addresses. IPv6 is based on 128-bit addressing and can support 340 undecillion, which is 340 trillion addresses. Having more addresses has grown in importance with the expansion of smart devices and connectivity. IPv6 provides more than enough globally unique IP addresses for every networked device currently on the planet, helping ensure providers can keep pace with the expected proliferation of IP-based devices. [Please refer here for more on IPv6]

 

3. Transmission Control Protocol (TCP) supports _____ data transfers?

(a) Full-duplex

(b) Half-duplex

(c) Simplex

(d) None of the above

Click here to view answer and explanation

Ans : (a)

Answer: (a) Full-duplex TCP is a transport-layer protocol that provides a reliable, full duplex, connection-oriented data transmission service. It is full-duplex because it can send and receive the data from both the side of connection simultaneously, without requiring line turnarounds, at the API level. "If there is a TCP connection between Process A on one host and Process B on another host, then application layer data can flow from Process A to Process B at the same time as application layer data flows from Process B to Process A". Another explanation: Full duplex or not is depend on the type of the Ethernet connection. If the switches and cabling support full duplex the TCP connection will work on full duplex but if those only support half duplex the TCP connection will work as half duplex. The speed and duplex setting are not features of TCP those are inherited and are part of a lower OSI layer, the transport layer. [Please refer here for details]

 

4. The field “Window” or “Window size” in TCP header refers to

(a) sender window

(b) receiver window

(c) congestion window

(d) none of the above

Click here to view answer and explanation

Ans : (b)

Answer: (b) receiver window The Window size is considered to be one of the most important flags within the TCP header. The size specifies the amount of data the destination is willing to accept from the sender. The sending host can send only that size of data before it must wait for an acknowledgment and window update from the receiving host. The window size flag consumes 16 bits. TCP supports flow control and the window size field is used for flow control.

 

5. The strength of signal falls off with distance over any transmission medium is called

(a) Attenuation

(b) Data rate

(c) Channel capacity

(d) Signal strength ratio

Click here to view answer and explanation

Ans : (a)

Answer: (a) Attenuation Attenuation is the loss of signal strength that occurs in networking cables or connections during transmission of signal from place to place. This happens when a signal loses energy overcoming the resistance of the medium in which it is traveling. Attenuation typically is measured in decibels (dB) or voltage and can occur due to a variety of factors.

 

********************

Related links

 

• Computer Networks MCQ home page

 

Define the term attenuation in networking

TCP supports full-duplex communication

State the key difference between TCP and UDP

How IPv6 is different from IPv4

Multiple choice questions in computer networks

Computer networks multiple choice questions with answers 06

Computer networks multiple choice questions with answers, entrance exam quiz questions on computer networks, solved exam questions on computer networks, MCQ in CN

Computer Networks MCQ - SET 06

1. The Domain Name Service (DNS) is an example of a

(a) transaction-oriented application-layer protocol

(b) session-oriented application-layer protocol

(c) transaction-oriented transport-layer protocol

(d) session-oriented transport-layer protocol

Click here to view answer and explanation

Ans : (a)

Answer: (a) transaction-oriented application-layer protocol Domain name service (DNS) is the application service that translates the IP address into a more recognized and memorable name. Whenever using the Internet, there are millions of DNS servers that translate any uniform resource locator (URL) typed into the location field of any Web browser into a specific IP address. The Domain Name System (or DNS) converts human readable domain names (like: www.google.com) into Internet Protocol (IP) addresses (like: 173.194.39.78).

 

2. Which of the following is an advantage of persistent HTTP connection?

(a) additional RTT's when obtaining multiple Web objects from different Web servers

(b) re-using an existing TCP connection for a Web transfer when it is possible to do so

(c) increased latency on subsequent requests

(d) None of the above

Click here to view answer and explanation

Ans : (b)

Answer: (b) re-using an existing TCP connection for a Web transfer when it is possible to do so A persistent connection takes 2 RTT for the connection and then transfers as many objects, as wanted, over this single connection. By opening and closing fewer TCP connections, CPU time is saved in routers and hosts (clients, servers, proxies, gateways, tunnels, or caches), and memory used for TCP protocol control blocks can be saved in hosts.

 

3. Which of the following is used by the network application BitTorrent?

(a) the peer-to-peer file sharing and TCP

(b) the peer-to-peer file sharing and UDP

(c) the client-server file sharing and TCP

(d) the client-server file sharing and UDP

Click here to view answer and explanation

Ans : (a)

Answer: (a) the peer-to-peer file sharing and TCP BitTorrent is a communication protocol for peer-to-peer file sharing (P2P), which enables users to distribute data and electronic files over the Internet in a decentralized manner. Rather than downloading a file from a single source server, the BitTorrent protocol allows users to join a "swarm" of hosts to upload and download from each other simultaneously. Refer Wikipedia.

 

4. In general, the throughput achieved by TCP for a
file transfer is

(a) inversely proportional to the average window size used during the transfer

(b) inversely proportional to the round trip time of the network path

(c) inversely proportional to the TCP segment size used for the transfer

(d) all of the above

Click here to view answer and explanation

Ans : (b)

Answer: (b) inversely proportional to the round trip time of the network path An important measure of the performance of a TCP connection is its throughput - the rate at which it transmits data from the sender to the receiver.  Clearly, throughput will depend on the value of w (window size). If a TCP sender transmits all w segments back-to-back, it must then wait for one round trip time (RTT) until it receives acknowledgments for these segments, at which point it can send w additional segments. If a connection transmits w segments of size MSS (maximum segment size) bytes every RTT seconds, then the connection's throughput, or transmission rate, is  (w*MSS)/RTT bytes per second.

 

5. For a TCP segment header, the minimum size is

(a) 20 bytes

(b) 25 bytes

(c) 10 – 12 bytes

(d) 16 bits

Click here to view answer and explanation

Ans : (a)

Answer: (a) 20 bytes The minimum size header is 5 words and the maximum is 15 words thus giving the minimum size of 20 bytes and maximum of 60 bytes, allowing for up to 40 bytes of options in the header.  TCP wraps each data packet with a header containing 10 mandatory fields totaling 20 bytes (or octets). Each header holds information about the connection and the current data being sent.

 

********************

Related links

 

• Computer Networks MCQ home page

 

What is an advantage of persistent HTTP connection?

What does DNS do?

Domain Name Service is a transaction oriented application layer protocol

How many RTTs a persistent http connection takes

What type of file sharing is done by BitTorrent

How do you relate TCP throughput and Round Trip Time