McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Computer Science Engineering (CSE) .
| 201. |
Which of the following is not a type of OSPF packet? |
| A. | hello |
| B. | link-state request |
| C. | link-state response |
| D. | link-state ack |
| Answer» C. link-state response | |
| Explanation: the five types of ospf packets are: hello, database description, link-state request, link-state update, and link-state ack. there is no link-state response packet; the neighbor router sends a link-state update packet as a response to the link-state request packet if there is an update in the routing table. | |
| 202. |
In OSPF header, which field is used to detect errors in the packet? |
| A. | type |
| B. | area id |
| C. | authentication type |
| D. | checksum |
| Answer» D. checksum | |
| Explanation: checksum field is used to detect errors. it makes sure that the data portions that are being sent are all in integrity. it can detect duplicated bits. once an error is detected, the sender has to re-transmit the data as it won’t receive an acknowledgement. | |
| 203. |
In OSPF database descriptor packet, if there are more database descriptor packets in the flow, ‘M’ field is set to |
| A. | 1 |
| B. | 0 |
| C. | more |
| D. | -1 |
| Answer» A. 1 | |
| Explanation: the “m” bit is the more bit, which indicates that there are more packets to be received in the descriptor packet flow whenever it is set to 1. there is also an “i” bit which indicates if the packet is first in the flow. | |
| 204. |
In OSPF database descriptor packet, which field is used to indicate that the router is master? |
| A. | m |
| B. | ms |
| C. | i |
| D. | options |
| Answer» B. ms | |
| Explanation: the ms bit is used to indicate if the origin of the packet is a master or a slave. if it is set to 1, the source of the packet is a master, and if it is set to 0, the source of the packet is a slave. | |
| 205. |
In OSPF database descriptor packet, which field is used to detect a missing packet? |
| A. | lsa header |
| B. | ms |
| C. | database descriptor sequence number |
| D. | options |
| Answer» C. database descriptor sequence number | |
| Explanation: sequence number field is used to detect a missing packet. the packets are to be received in order of the sequence number, so if the receiver detects that there is a sequence number skipped or missing in the order, it stops processing the further received packets and informs the sender to retransmit the packets in sequence. | |
| 206. |
The size of an IP address in IPv6 is |
| A. | 4 bytes |
| B. | 128 bits |
| C. | 8 bytes |
| D. | 100 bits |
| Answer» B. 128 bits | |
| Explanation: an ipv6 address is 128 bits long. therefore, 2128 i.e. 340 undecillion addresses are possible in ipv6. ipv4 has only 4 billion possible addresses and ipv6 would be a brilliant alternative in case ipv4 runs out of possible new addresses. | |
| 207. |
The header length of an IPv6 datagram is |
| A. | 10bytes |
| B. | 25bytes |
| C. | 30bytes |
| D. | 40bytes |
| Answer» D. 40bytes | |
| Explanation: ipv6 datagram has fixed header length of 40bytes, which results in faster processing of the datagram. there is one fixed header and optional headers which may or may not exist. the fixed header contains the mandatory essential information about the | |
| 208. |
In the IPv6 header, the traffic class field is similar to which field in the IPv4 header? |
| A. | fragmentation field |
| B. | fast-switching |
| C. | tos field |
| D. | option field |
| Answer» C. tos field | |
| Explanation: the traffic class field is used to specify the priority of the ip packet which is a similar functionality to the type of service field in the ipv4 header. it’s an 8-bit field and its values are not defined in the rfc 2460. | |
| 209. |
IPv6 does not use type of address. |
| A. | broadcast |
| B. | multicast |
| C. | anycast |
| D. | unicast |
| Answer» A. broadcast | |
| Explanation: there is no concept of broadcast address in ipv6. instead, there is an anycast address in ipv6 which allows sending messages to a group of devices but not all devices in a network. anycast address is not standardized in ipv4. | |
| 210. |
Which among the following features is |
| A. | hop limit |
| B. | ttl |
| C. | next header |
| D. | type of traffic |
| Answer» A. hop limit | |
| Explanation: the hop limit value is decremented by one by a router when the datagram is forwarded by the router. when the value becomes zero the datagram is discarded. the field is 8-bits wide, so an ipv6 packet can live up to 255 router hops only. | |
| 211. |
Dual-stack approach refers to |
| A. | implementing ipv4 with 2 stacks |
| B. | implementing ipv6 with 2 stacks |
| C. | node has both ipv4 and ipv6 support |
| D. | implementing a mac address with 2 stacks |
| Answer» C. node has both ipv4 and ipv6 support | |
| Explanation: dual-stack is one of the approaches used to support ipv6 in already existing systems. isps are using it as a method to transfer from ipv4 to ipv6 completely eventually due to the lower number of possible available addresses in ipv4. | |
| 212. |
The field determines the lifetime of IPv6 datagram |
| A. | use dual-stack approach |
| B. | tunneling |
| C. | no solution |
| D. | replace the system |
| Answer» B. tunneling | |
| Explanation: the ipv4 routers can form a tunnel in which at the sender’s side, the ipv6 datagram is encapsulated in to ipv4, and at the receiver’s side of the tunnel, the ipv4 packet is stripped and the ipv6 packet is sent to the receiver. | |
| 213. |
Teredo is an automatic tunneling technique. In each client the obfuscated IPv4 address is represented by bits |
| A. | 96 to 127 |
| B. | 0 to 63 |
| C. | 80 to 95 |
| D. | 64 to 79 |
| Answer» A. 96 to 127 | |
| Explanation: teredo is a technique through which gives the possibility for full ipv6 network connectivity to ipv6 capable hosts which are currently on an ipv4 network. bits 96 to 127 in the datagram represents obfuscated 1pv4 address of the ipv4 network. | |
| 214. |
An endpoint of an inter-process communication flow across a computer network is called |
| A. | socket |
| B. | pipe |
| C. | port |
| D. | machine |
| Answer» A. socket | |
| Explanation: socket is one end point in a two way communication link in the network. tcp layer can identify the application that data is destined to be sent by using the port number that is bound to socket. | |
| 215. |
Which one of the following is a version of UDP with congestion control? |
| A. | datagram congestion control protocol |
| B. | stream control transmission protocol |
| C. | structured stream transport |
| D. | user congestion control protocol |
| Answer» A. datagram congestion control protocol | |
| Explanation: the datagram congestion control is a transport layer protocol which deals with reliable connection setup, teardown, congestion control, explicit congestion notification, and feature negotiation. it is used in modern day systems where there are really high chances of congestion. the protocol was last updated in the year 2008. | |
| 216. |
Which of the following is a transport layer protocol? |
| A. | stream control transmission protocol |
| B. | internet control message protocol |
| C. | neighbor discovery protocol |
| D. | dynamic host configuration protocol |
| Answer» A. stream control transmission protocol | |
| Explanation: the stream control transmission protocol (sctp) is a transport layer protocol used in networking system where streams of data are to be continuously transmitted between two connected network nodes. some of the other transport layer protocols are rdp, rudp, tcp, dccp, udp etc. | |
| 217. |
2 USER DATAGRAM PROTOCOLS (UDP) |
| A. | connection-oriented |
| B. | unreliable |
| C. | transport layer protocol |
| D. | low overhead |
| Answer» A. connection-oriented | |
| Explanation: udp is an unreliable, connectionless transport layer protocol that provides message-based data transmission. tcp is an example of connection-oriented protocols. | |
| 218. |
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’s |
| Answer» A. string of characters | |
| Explanation: 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. | |
| 219. |
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 checking |
| Answer» D. demultiplexing and error checking | |
| Explanation: 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. | |
| 220. |
What is the main advantage of UDP? |
| A. | more overload |
| B. | reliable |
| C. | low overhead |
| D. | fast |
| Answer» C. low overhead | |
| 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. | |
| 221. |
What is the header size of a UDP packet? |
| A. | 8 bytes |
| B. | 8 bits |
| C. | 16 bytes |
| D. | 124 bytes |
| Answer» A. 8 bytes | |
| Explanation: 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. | |
| 222. |
The port number is “ephemeral port number”, if the source host is |
| A. | ntp |
| B. | echo |
| C. | server |
| D. | client |
| Answer» D. client | |
| Explanation: 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. | |
| 223. |
“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 data |
| Answer» D. udp header plus data | |
| 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). | |
| 224. |
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 length |
| Answer» A. udp length = ip length – ip header’s length | |
| 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. | |
| 225. |
The field is used to detect errors over the entire user datagram. |
| A. | udp header |
| B. | checksum |
| C. | source port |
| D. | destination port |
| Answer» B. checksum | |
| Explanation: 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 | |
| 226. |
Which of the following is false with respect to TCP? |
| A. | connection-oriented |
| B. | process-to-process |
| C. | transport layer protocol |
| D. | unreliable |
| Answer» 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. | |
| 227. |
In TCP, sending and receiving data is done as |
| A. | stream of bytes |
| B. | sequence of characters |
| C. | lines of data |
| D. | packets |
| Answer» A. stream of bytes | |
| 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. | |
| 228. |
TCP groups a number of bytes together into a packet called |
| A. | packet |
| B. | buffer |
| C. | segment |
| D. | stack |
| Answer» C. segment | |
| Explanation: a segment may be collection of data from many send () statements. tcp transmits each segment as a stream of bytes. | |
| 229. |
Communication offered by TCP is |
| A. | full-duplex |
| B. | half-duplex |
| C. | semi-duplex |
| D. | byte by byte |
| Answer» A. full-duplex | |
| Explanation: 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. | |
| 230. |
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. | 11001 |
| Answer» B. 10001 | |
| 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. | |
| 231. |
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’s |
| Answer» D. sequence of zero’s and one’s | |
| Explanation: 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 | |
| 232. |
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 ones |
| Answer» C. sequence number of the next byte to be received | |
| 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. | |
| 233. |
Two broad categories of congestion control are |
| A. | open-loop and closed-loop |
| B. | open-control and closed-control |
| C. | active control and passive control |
| D. | active loop and passive loop |
| Answer» A. open-loop and closed-loop | |
| Explanation: open loop congestion control techniques are used to prevent congestion before it even happens by enforcing certain policies. closed loop congestion control techniques are used to treat congestion after it has happened. | |
| 234. |
Retransmission of packets must not be done when |
| A. | packet is lost |
| B. | packet is corrupted |
| C. | packet is needed |
| D. | packet is error-free |
| Answer» D. packet is error-free | |
| Explanation: retransmission refers to the sender having to resend the packet to the receiver. it needs to be done only when some anomaly occurs with the packet like when the packet is lost or corrupted. | |
| 235. |
In Go-Back-N window, when the timer of the packet times out, several packets have to be resent even some may have arrived safe. Whereas in Selective Repeat window, the sender resends |
| A. | packet which are not lost |
| B. | only those packets which are lost or corrupted |
| C. | packet from starting |
| D. | all the packets |
| Answer» B. only those packets which are lost or corrupted | |
| Explanation: in selective repeat, the sender side uses a searching algorithm to find the packets which need to be retransmitted based on the negative acknowledgements received and then resends only those packets thus saving bandwidth. | |
| 236. |
Closed-Loop control mechanisms try to |
| A. | remove after congestion occurs |
| B. | remove after sometime |
| C. | prevent before congestion occurs |
| D. | prevent before sending packets |
| Answer» A. remove after congestion occurs | |
| Explanation: in closed loop congestion control, methods are implemented to remove congestion after it occurs. some of the methods used are backpressure and choke packet. | |
| 237. |
The technique in which a congested node stops receiving data from the immediate upstream node or nodes is called as |
| A. | admission policy |
| B. | backpressure |
| C. | forward signaling |
| D. | backward signaling |
| Answer» B. backpressure | |
| Explanation: in this closed loop congestion control technique, the congested node propagates in the opposite direction of the data flow to inform the predecessor node to reduce the flow of packets. this is why this technique is called a node-to-node congestion control technique. | |
| 238. |
The packet sent by a node to the source to inform it of congestion is called |
| A. | explicit |
| B. | discard |
| C. | choke |
| D. | backpressure |
| Answer» C. choke | |
| Explanation: choke packet is sent by a node to the source to inform it of congestion. two choke packet techniques can be used for the operation called hop-by-hop choke packet and source choke packet. | |
| 239. |
In the slow-start algorithm, the size of the congestion window increases until it reaches a threshold. |
| A. | exponentially |
| B. | additively |
| C. | multiplicatively |
| D. | suddenly |
| Answer» A. exponentially | |
| Explanation: in slow-start algorithm, the size of the congestion window increases exponentially until it reaches a threshold. | |
| 240. |
Which is not a application layer protocol? |
| A. | http |
| B. | smtp |
| C. | ftp |
| D. | tcp |
| Answer» D. tcp | |
| Explanation: tcp is transport layer protocol. | |
| 241. |
The packet of information at the application layer is called |
| A. | packet |
| B. | message |
| C. | segment |
| D. | frame |
| Answer» B. message | |
| Explanation: for application, presentation and session layers there is no data format for message. message is message as such in these three layers. but when it comes to transport, network, data and physical layer they have data in format of segments, packets, frames and bits respectively. | |
| 242. |
Which one of the following is an architecture paradigms? |
| A. | peer to peer |
| B. | client-server |
| C. | http |
| D. | both peer-to-peer & client-server |
| Answer» D. both peer-to-peer & client-server | |
| Explanation: http is a protocol. | |
| 243. |
Application layer offers service. |
| A. | end to end |
| B. | process to process |
| C. | both end to end and process to process |
| D. | none of the mentioned |
| Answer» A. end to end | |
| Explanation: end to end service is provided in the application layer. whereas process to process service is provided at the transport layer. | |
| 244. |
E-mail is |
| A. | loss-tolerant application |
| B. | bandwidth-sensitive application |
| C. | elastic application |
| D. | none of the mentioned |
| Answer» C. elastic application | |
| Explanation: because it can work with available throughput. | |
| 245. |
Pick the odd one out. |
| A. | file transfer |
| B. | file download |
| C. | |
| D. | interactive games |
| Answer» D. interactive games | |
| Explanation: file transfer, file download and email are services provided by the application layer and there are message and data oriented. | |
| 246. |
Which of the following is an application layer service? |
| A. | network virtual terminal |
| B. | file transfer, access, and management |
| C. | mail service |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: the services provided by the application layer are network virtual terminal, file transfer, access and management, mail services, directory services, various file and data operations. | |
| 247. |
Which is a time-sensitive service? |
| A. | file transfer |
| B. | file download |
| C. | |
| D. | internet telephony |
| Answer» D. internet telephony | |
| Explanation: internet telephony is loss- tolerant other applications are not. | |
| 248. |
Transport services available to applications in one or another form |
| A. | reliable data transfer |
| B. | timing |
| C. | security |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: the transport services that are provided to application are reliable data transfer, security and timing. these are very important for proper end to end services. | |
| 249. |
Electronic mail uses which Application layer protocol? |
| A. | smtp |
| B. | http |
| C. | ftp |
| D. | sip |
| Answer» A. smtp | |
| Explanation: email uses various protocols like smtp, imap and pop. the most prominent one used in application layer is smtp. | |
| 250. |
RMI stands for? |
| A. | remote mail invocation |
| B. | remote message invocation |
| C. | remaining method invocation |
| D. | remote method invocation |
| Answer» D. remote method invocation | |
| Explanation: the rmi (remote method invocation) is an api that provides a mechanism to create distributed applications. | |
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