Explore topic-wise InterviewSolutions in .

This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

1.

Which of the following organizations is primarily concerned with military encryption systems?(a) NSA(b) NIST(c) IEEE(d) ITUThis question was posed to me in unit test.The above asked question is from AH and ESP Protocols topic in portion Transport Layer of Computer Network

Answer»

Right OPTION is (a) NSA

Easiest explanation: The NSA is primarily responsible for military encryption systems. The NSA DESIGNS evaluates, and IMPLEMENTS encryption systems for the military and government agencies with high SECURITY needs.
Discussion
2.

In computer security _______ means that the information in a computer system only be accessible for reading by authorized parities.(a) confidentiality(b) integrity(c) availability(d) authenticityI got this question in exam.This key question is from AH and ESP Protocols in portion Transport Layer of Computer Network

Answer»

Right choice is (a) CONFIDENTIALITY

The explanation: Confidentiality means that the ASSETS can only be accessed by authorized parties. INTEGRITY means that computer system assets can be modified only by authorized PARITIES. Availability refers to the accessibility of the resource to the authorized parties. Authenticity means that the ASSET is not unethically changed.
Discussion
3.

In computer security _______ means that computer system assets can be modified only by authorized parities.(a) confidentiality(b) integrity(c) availability(d) authenticityThis question was addressed to me by my school teacher while I was bunking the class.Origin of the question is AH and ESP Protocols topic in portion Transport Layer of Computer Network

Answer»

The correct choice is (b) integrity

To explain: Integrity MEANS that computer system assets can be MODIFIED only by authorized parities. CONFIDENTIALITY means that the assets can only be accessed by authorized parties. Availability REFERS to the accessibility of the resource to the authorized parties. Authenticity means that the asset is not unethically changed.
Discussion
4.

ESP does not provide ________(a) source authentication(b) data integrity(c) privacy(d) error controlThis question was addressed to me during an online interview.This interesting question is from AH and ESP Protocols topic in chapter Transport Layer of Computer Network

Answer»

Right option is (d) error control

To elaborate: The ESP PROVIDES DATA confidentiality, INTEGRITY and authentication. It provides confidentiality through encryption.ESP can operate in TWO modes, transport mode and tunnel mode.
Discussion
5.

IP Security operates in which layer of the OSI model?(a) Network(b) Transport(c) Application(d) PhysicalThe question was asked during an interview.My question is based upon AH and ESP Protocols topic in division Transport Layer of Computer Network

Answer»

Right CHOICE is (a) Network

The best I can explain: IPSec is a set of protocols used to PROVIDE authentication, data integrity and confidentiality between TWO machines in an IP network. In the TCP/IP model, it PROVIDES security at the IP layer i.e. the network layer.
Discussion
6.

IPsec defines two protocols: _______ and ________(a) AH; SSL(b) PGP; ESP(c) AH; ESP(d) PGP; SSLThe question was posed to me in an online interview.My doubt is from AH and ESP Protocols topic in division Transport Layer of Computer Network

Answer»

The CORRECT choice is (c) AH; ESP

Explanation: AH ensures that there is no retransmission of data from an UNAUTHORIZED source, and protects against data tampering. ESP provides with content protection and ensures that there is INTEGRITY and confidentiality for the message.
Discussion
7.

______ provides authentication at the IP level.(a) AH(b) ESP(c) PGP(d) SSLThe question was posed to me in an interview.Enquiry is from AH and ESP Protocols topic in portion Transport Layer of Computer Network

Answer»

Right option is (a) AH

To elaborate: The Authentication Header (AH) AUTHENTICATES the origin of data, and guarantees the INTEGRITY of the INFORMATION that’s being sent using IPSec. It also PROVIDES anti-reply security.
Discussion
8.

Which two types of IPsec can be used to secure communications between two LANs?(a) AH tunnel mode(b) ESP tunnel mode(c) Both AH tunnel mode and ESP tunnel mode(d) ESP transport modeI got this question by my college professor while I was bunking the class.This intriguing question originated from AH and ESP Protocols in section Transport Layer of Computer Network

Answer» RIGHT choice is (c) Both AH tunnel mode and ESP tunnel mode

The explanation: The AH and ESP tunnel mode IPSec should be used for data transfer purpose, option d is for integrity & confidentiality purpose. Tunnel mode provides security for the entire original IP packet unlike transport mode which is not as SECURE as it only encrypts the data portion and not the whole packet.
Discussion
9.

Which two types of encryption protocols can be used to secure the authentication of computers using IPsec?(a) Kerberos V5(b) SHA(c) MD5(d) Both SHA and MD5This question was addressed to me in homework.My question is based upon AH and ESP Protocols topic in section Transport Layer of Computer Network

Answer»

Correct OPTION is (d) Both SHA and MD5

To elaborate: SHA or MD5 can be used. Kerberos V5 is an authentication PROTOCOL, not an ENCRYPTION protocol; therefore, answer A is incorrect. CERTIFICATES are a type of authentication that can be used with IPsec, not an encryption protocol; therefore, answer B is incorrect.
Discussion
10.

Which mode of IPsec should you use to assure the security and confidentiality of data within the same LAN?(a) AH transport mode(b) ESP transport mode(c) ESP tunnel mode(d) AH tunnel modeThe question was posed to me in semester exam.My query is from AH and ESP Protocols in chapter Transport Layer of Computer Network

Answer»

The correct option is (b) ESP TRANSPORT mode

The best I can explain: ESP transport mode should be used to ensure the INTEGRITY and confidentiality of data that is exchanged within the same LAN. ESP tunnel mode is comparatively more SECURE and should be used to assure the security of the data within different LANs.
Discussion
11.

The ______ field is used to detect errors over the entire user datagram.(a) udp header(b) checksum(c) source port(d) destination portI got this question at a job interview.This interesting question is from UDP topic in chapter Transport Layer of Computer Network

Answer»

The correct choice is (b) checksum

The EXPLANATION is: Checksum FIELD is USED to detect errors over the entire USER datagram. Though it is not as efficient as CRC which is used in TCP, it gets the job done for the UDP datagram as UDP doesn’t have to ensure the delivery of the packet.
Discussion
12.

Which is the correct expression for the length of UDP datagram?(a) UDP length = IP length – IP header’s length(b) UDP length = UDP length – UDP header’s length(c) UDP length = IP length + IP header’s length(d) UDP length = UDP length + UDP header’s lengthI have been asked this question in my homework.I want to ask this question from UDP topic in portion Transport Layer of Computer Network

Answer»

Correct option is (a) UDP length = IP length – IP header’s length

The best explanation: A USER DATAGRAM is encapsulated in an IP datagram. There is a field in the IP header that DEFINES the total length of the IP packet. There is another field in the IP header that defines the length of the header. So if we subtract the length of the IP header that is encapsulated in the IP packet, we get the length of UDP datagram.
Discussion
13.

“Total length” field in UDP packet header is the length of _________(a) Only UDP header(b) Only data(c) Only checksum(d) UDP header plus dataI had been asked this question during an online interview.This interesting question is from UDP topic in section Transport Layer of Computer Network

Answer»

Right option is (d) UDP header PLUS data

For explanation: Total length is the 16 bit field which contains the length of UDP header and the data. The maximum value of the Total length field and the maximum size of a UDP DATAGRAM is 65,535 bytes (8 BYTE header + 65,527 bytes of data).
Discussion
14.

The port number is “ephemeral port number”, if the source host is _______(a) NTP(b) Echo(c) Server(d) ClientThe question was posed to me in unit test.This intriguing question originated from UDP in chapter Transport Layer of Computer Network

Answer»

Correct OPTION is (d) Client

To explain: Port numbers from 1025 to 5000 are USED as EPHEMERAL port numbers in Windows Operating SYSTEM. Ephemeral port numbers are short-lived port numbers which can be used for clients in a UDP system where there are temporary clients all the time.
Discussion
15.

What is the header size of a UDP packet?(a) 8 bytes(b) 8 bits(c) 16 bytes(d) 124 bytesI had been asked this question in semester exam.Origin of the question is UDP topic in chapter Transport Layer of Computer Network

Answer»

The correct answer is (a) 8 BYTES

For explanation I would say: The fixed size of the UDP packet HEADER is 8 bytes. It CONTAINS four two-byte fields: Source port address, Destination port address, Length of packet, and checksum.
Discussion
16.

Port number used by Network Time Protocol (NTP) with UDP is ________(a) 161(b) 123(c) 162(d) 124I got this question in quiz.Origin of the question is UDP in portion Transport Layer of Computer Network

Answer»

The correct answer is (b) 123

The BEST I can explain: The Network TIME PROTOCOL is a clock synchronization network protocol implemented by USING UDP port number 123 to send and receive time stamps.
Discussion
17.

What is the main advantage of UDP?(a) More overload(b) Reliable(c) Low overhead(d) FastI got this question by my college director while I was bunking the class.My query is from UDP topic in division Transport Layer of Computer Network

Answer»

Correct answer is (c) LOW OVERHEAD

The explanation: As UDP does not PROVIDE assurance of DELIVERY of packet, reliability and other services, the overhead taken to provide these services is REDUCED in UDP’s operation. Thus, UDP provides low overhead, and higher speed.
Discussion
18.

Beyond IP, UDP provides additional services such as _______(a) Routing and switching(b) Sending and receiving of packets(c) Multiplexing and demultiplexing(d) Demultiplexing and error checkingI got this question during a job interview.Origin of the question is UDP in portion Transport Layer of Computer Network

Answer»

Correct choice is (d) Demultiplexing and error checking

The BEST I can explain: De-multiplexing is the delivering of received segments to the correct APPLICATION layer PROCESSES at the recipients end using UDP. Error checking is DONE through checksum in UDP.
Discussion
19.

Return value of the UDP port “Chargen” is _______(a) String of characters(b) String of integers(c) Array of characters with integers(d) Array of zero’s and one’sI had been asked this question in a job interview.My question comes from UDP topic in division Transport Layer of Computer Network

Answer» RIGHT choice is (a) STRING of CHARACTERS

The BEST I can explain: Using Chargen with UDP on port 19, the server sends a UDP datagram containing a random number of characters every time it receives a datagram from the connecting host. The number of characters is between 0 and 512.
Discussion
20.

Which of the following is false with respect to UDP?(a) Connection-oriented(b) Unreliable(c) Transport layer protocol(d) Low overheadThe question was asked in quiz.This interesting question is from UDP topic in section Transport Layer of Computer Network

Answer»

Right answer is (a) Connection-oriented

Easiest explanation: UDP is an unreliable, connectionless TRANSPORT layer PROTOCOL that provides message-based data TRANSMISSION. TCP is an EXAMPLE of connection-oriented protocols.
Discussion
21.

What allows TCP to detect lost segments and in turn recover from that loss?(a) Sequence number(b) Acknowledgment number(c) Checksum(d) Both Sequence & Acknowledgment numberThis question was posed to me in an online quiz.Question is taken from TCP-2 topic in division Transport Layer of Computer Network

Answer»

Right option is (b) Acknowledgment NUMBER

Best explanation: TCP header contains separate FIELDS for sequence number and acknowledgment number. Comparing these VALUES is what allows TCP to detect lost segments and in TURN recover from that loss. After detecting the lost segments, the recovery may require RETRANSMISSION of the lost segments of data.
Discussion
22.

The sizes of source and destination port address in TCP header are ___________ respectively.(a) 16-bits and 32-bits(b) 16-bits and 16-bits(c) 32-bits and 16-bits(d) 32-bits and 32-bitsThis question was addressed to me in an online interview.My question is from TCP-2 in portion Transport Layer of Computer Network

Answer»

The CORRECT choice is (B) 16-bits and 16-bits

The best explanation: All PORT addresses are of 16 bits and they specify the type of service being used by the network entity. For example, port 21 is used for FTP connections and port 25 is used for ICMP connections.
Discussion
23.

SYNC flooding attack belongs to a type of security attack known as ___________(a) SYNC flooding attack(b) Active attack(c) Passive attack(d) Denial-of-service attackI got this question in exam.My doubt stems from TCP-2 topic in chapter Transport Layer of Computer Network

Answer»

The correct choice is (d) Denial-of-SERVICE attack

For explanation I WOULD say: During SYNC flooding the system collapses and DENIES service to every request, making it a DOS attack. Some other DoS attacks are bandwidth flooding, connection flooding and UDP flooding.
Discussion
24.

A malicious attacker sends a large number of SYNC segments to a server, pretending that each of them is coming from a different client by faking the source IP address in the datagram. Which type of attack is being performed in this situation?(a) SYNC flooding attack(b) Active attack(c) Passive attack(d) Denial-of-service attackI had been asked this question by my school principal while I was bunking the class.This interesting question is from TCP-2 topic in chapter Transport Layer of Computer Network

Answer»

Right choice is (a) SYNC flooding attack

To explain I would say: SYNC flooding attack is a FORM of Denial of Service attack. Due to the overflow of SYNC SEGMENTS sent to the server, the victims are not ABLE to request for a connection to the server, thus resulting in Denial of Service.
Discussion
25.

In Three-Way Handshaking process, the situation where both the TCP’s issue an active open is ___________(a) Mutual open(b) Mutual Close(c) Simultaneous open(d) Simultaneous closeI had been asked this question in an interview.My doubt is from TCP-2 topic in chapter Transport Layer of Computer Network

Answer»

Correct choice is (c) Simultaneous open

The best I can explain: In simultaneous open situation, TWO NODES send an SYN signal to each other and start a TCP CONNECTION. Here, both TCP nodes transmit a SYNC+ACK SEGMENT to each other and a connection is established between them. This doesn’t happen usually, because both sides have to know which port on the other SIDE to send to.
Discussion
26.

A client that wishes to connect to an open server tells its TCP that it needs to be connected to that particular server. The process is called ___________(a) Active open(b) Active close(c) Passive close(d) Passive openThis question was posed to me in an international level competition.I'm obligated to ask this question of TCP-2 topic in portion Transport Layer of Computer Network

Answer» RIGHT answer is (a) ACTIVE OPEN

The best I can explain: This is the second step in the Three-Way Handshaking process and is DONE by the client once it finds the open server and picks an ISN. The Server acknowledges the clients REQUEST, and then picks an ISN and synchronizes it with the Client. At last, the Client acknowledges the servers ISN.
Discussion
27.

The server program tells its TCP that it is ready to accept a connection. This process is called ___________(a) Active open(b) Active close(c) Passive close(d) Passive openI had been asked this question by my college professor while I was bunking the class.Query is from TCP-2 topic in portion Transport Layer of Computer Network

Answer»

The correct answer is (d) Passive open

To elaborate: This is the first step in the Three-Way Handshaking process and is started by the SERVER. Then the Client picks an ISN (Initial SEQUENCE Number) and synchronizes (SHARES) it with the Server REQUESTING a connection. The Server acknowledges the clients ISN, and then picks an ISN and synchronizes it with the Client. At last, the Client acknowledges the servers ISN.
Discussion
28.

Connection establishment in TCP is done by which mechanism?(a) Flow control(b) Three-Way Handshaking(c) Forwarding(d) SynchronizationI had been asked this question by my school principal while I was bunking the class.I would like to ask this question from TCP-2 topic in section Transport Layer of Computer Network

Answer» RIGHT answer is (b) Three-Way Handshaking

The explanation is: A three-way handshake allows both, the SERVER and the client to CHOOSE their INITIAL Sequence Number and inform about it to the other party. This won’t be possible using the two-way handshake MECHANISM.
Discussion
29.

Size of TCP segment header ranges between ___________(a) 16 and 32 bytes(b) 16 and 32 bits(c) 20 and 60 bytes(d) 20 and 60 bitsI had been asked this question in my homework.The above asked question is from TCP-2 topic in section Transport Layer of Computer Network

Answer»

The CORRECT choice is (c) 20 and 60 bytes

For explanation I would say: The size of the HEADER can be 20 bytes at a minimum if there are no options and can GO up to 60 bytes at maximum with 40 bytes in the options field. The header contains all the control information required to ensure ORDERED, error-free and reliable delivery of the segment.
Discussion
30.

The receiver of the data controls the amount of data that are to be sent by the sender is referred to as ___________(a) Flow control(b) Error control(c) Congestion control(d) Error detectionI had been asked this question by my school teacher while I was bunking the class.This interesting question is from TCP-2 in portion Transport Layer of Computer Network

Answer»

Correct answer is (a) FLOW control

Best explanation: Flow control is done to prevent the RECEIVER from being OVERFLOWED with data. It is done USING VARIOUS open-loop (prevention) methods and closed-loop (recovery) methods.
Discussion
31.

The value of acknowledgement field in a segment defines _______(a) sequence number of the byte received previously(b) total number of bytes to receive(c) sequence number of the next byte to be received(d) sequence of zeros and onesThe question was posed to me in a job interview.I'd like to ask this question from TCP-1 topic in portion Transport Layer of Computer Network

Answer» CORRECT choice is (C) sequence number of the next byte to be received

For explanation: The ACKNOWLEDGEMENT FIELD in a segment DEFINES the sequence number of the byte which is to be received next i.e. sequence number of byte that the sender should transmit next.
Discussion
32.

Bytes of data being transferred in each connection are numbered by TCP. These numbers start with a _________(a) Fixed number(b) Random sequence of 0’s and 1’s(c) One(d) Sequence of zero’s and one’sI got this question in an interview.My query is from TCP-1 in section Transport Layer of Computer Network

Answer» RIGHT option is (d) Sequence of zero’s and one’s

The best I can explain: One might expect the sequence number of the first BYTE in the stream to be 0, or 1. But that does not happen in TCP, Instead, the SENDER has to choose an Initial Sequence Number (ISN), which is basically a random 32 bit sequence of 0’s and 1’s, during the connection handshake.
Discussion
33.

Suppose a TCP connection is transferring a file of 1000 bytes. The first byte is numbered 10001. What is the sequence number of the segment if all data is sent in only one segment?(a) 10000(b) 10001(c) 12001(d) 11001The question was posed to me at a job interview.I want to ask this question from TCP-1 in chapter Transport Layer of Computer Network

Answer» CORRECT option is (b) 10001

Easiest explanation: The SEQUENCE number given to FIRST byte of a SEGMENT, with RESPECT to its order among the previous segments, is the sequence number of that segment.
Discussion
34.

In segment header, sequence number and acknowledgement number fields refer to _______(a) Byte number(b) Buffer number(c) Segment number(d) AcknowledgmentThis question was addressed to me in exam.Question is taken from TCP-1 in portion Transport Layer of Computer Network

Answer»

The correct option is (a) Byte NUMBER

To EXPLAIN I would SAY: As TCP has to ensure ordered delivery of PACKETS, sequence number and acknowledgement number are used to identify the byte number of the packet in the STREAM of bytes being transmitted.
Discussion
35.

To achieve reliable transport in TCP, ___________ is used to check the safe and sound arrival of data.(a) Packet(b) Buffer(c) Segment(d) AcknowledgmentI have been asked this question by my school principal while I was bunking the class.This interesting question is from TCP-1 in division Transport Layer of Computer Network

Answer»

Correct answer is (d) Acknowledgment

Best explanation: Acknowledgment mechanism is used to check the safe and SOUND arrival of data. The sender actively checks for acknowledgement from the receiver and once a SPECIFIC TIME period has PASSED, it retransmits the data.
Discussion
36.

Communication offered by TCP is ________(a) Full-duplex(b) Half-duplex(c) Semi-duplex(d) Byte by byteThe question was asked in an internship interview.The origin of the question is TCP-1 in division Transport Layer of Computer Network

Answer» CORRECT option is (a) Full-duplex

The explanation is: Data can flow both the directions at the same time during a TCP communication HENCE, it is full-duplex. This is the REASON why TCP is used in systems that require full-duplex operation such as e-mail systems.
Discussion
37.

TCP groups a number of bytes together into a packet called _______(a) Packet(b) Buffer(c) Segment(d) StackThe question was posed to me during an online interview.My question is from TCP-1 in portion Transport Layer of Computer Network

Answer» CORRECT choice is (c) SEGMENT

Explanation: A segment may be collection of data from MANY send () STATEMENTS. TCP transmits each segment as a stream of BYTES.
Discussion
38.

TCP process may not write and read data at the same speed. So we need __________ for storage.(a) Packets(b) Buffers(c) Segments(d) StacksI have been asked this question during an interview.My question comes from TCP-1 in division Transport Layer of Computer Network

Answer» RIGHT ANSWER is (b) Buffers

The best I can EXPLAIN: A TCP receiver has a receive buffer that is used to store the UNPROCESSED incoming packets in case the sender is sending packets faster than the processing rate of the received packets.
Discussion
39.

In TCP, sending and receiving data is done as _______(a) Stream of bytes(b) Sequence of characters(c) Lines of data(d) PacketsI got this question in homework.Query is from TCP-1 topic in portion Transport Layer of Computer Network

Answer»

Right option is (a) Stream of bytes

For explanation: TCP provides stream oriented delivery between hosts communicating VIA an IP network and there are no message boundaries. TCP can concatenate data from a number of SEND () COMMANDS into one stream of data and still TRANSMIT it RELIABLY.
Discussion
40.

Which of the following is false with respect to TCP?(a) Connection-oriented(b) Process-to-process(c) Transport layer protocol(d) UnreliableI got this question during an interview.My question is from TCP-1 in portion Transport Layer of Computer Network

Answer»

The correct CHOICE is (d) Unreliable

Explanation: TCP is a transport LAYER protocol that provides RELIABLE and ORDERED delivery of a stream of bytes between hosts communicating VIA an IP network.
Discussion