Computer Science/IT MCQs
Topic Notes: Computer Science/IT
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
11
How does the QUIC protocol handle the 'Head-of-Line Blocking' issue found in TCP?
Answer:
By implementing multiple independent streams within a single connection over UDP.
In TCP, if one packet is lost, all subsequent packets in the buffer are held up until the lost packet is retransmitted (Head-of-Line Blocking). QUIC runs over UDP and supports multiple streams within one connection. If a packet in one stream is lost, it only affects that specific stream, allowing other streams to continue processing data without delay.
12
What is the primary goal of the 'Nagle's Algorithm'?
Answer:
To reduce the number of small packets sent over the network by buffering them.
Nagle's algorithm is used to improve the efficiency of TCP/IP networks by reducing the number of very small packets (like those containing only one character from a telnet session). It works by delaying the sending of small segments until they can be combined into a larger segment or until an ACK is received for previous data.
13
Which protocol is primarily used for distributing labels in a Multiprotocol Label Switching (MPLS) network?
Answer:
LDP
The Label Distribution Protocol (LDP) is used by Label Switch Routers (LSRs) to exchange label mapping information. This allows the routers to build a Label Forwarding Information Base (LFIB) to forward packets based on labels rather than IP addresses, facilitating high-speed switching and traffic engineering.
14
What does the 'ACK' flag in a TCP header indicate?
Answer:
That the acknowledgment field in the header is valid and contains the next expected sequence number.
In TCP, the ACK flag is set in almost every packet after the initial SYN. When this bit is set to 1, it means the 32-bit 'Acknowledgment Number' field contains the sequence number that the sender of the ACK is expecting to receive next, effectively confirming that all prior data has been received correctly.
15
Which of the following is true about 'Multiplexing' in the Transport Layer?
Answer:
It allows multiple applications to use the network simultaneously through the use of port numbers.
Multiplexing at the Transport Layer (TCP/UDP) allows a single host with a single IP address to support many concurrent applications. By using unique port numbers for each connection, the transport layer can 'demultiplex' incoming data and deliver it to the correct application process.
16
What is the 'MTU' (Maximum Transmission Unit)?
Answer:
The largest size of a protocol data unit (PDU) that can be communicated in a single network layer transaction.
The MTU is the maximum size (in bytes) of a packet or frame that can be sent over a specific physical medium. For standard Ethernet, the MTU is typically 1500 bytes. If a packet is larger than the MTU of a link it needs to cross, it must be fragmented (in IPv4) or dropped (in IPv6).
17
In OSPF, what is the purpose of an 'Area Border Router' (ABR)?
Answer:
To connect one or more OSPF areas to the backbone area (Area 0).
An Area Border Router (ABR) is a router located on the border between OSPF areas. It maintains separate link-state databases for each area it belongs to and summarizes routing information from one area to another, specifically connecting non-backbone areas to the mandatory backbone area (Area 0).
18
In cellular networks, what is a 'Handoff' (or Handover)?
Answer:
The process of transferring an active call or data session from one base station to another as the user moves.
Handoff is a critical feature of mobile networks. As a mobile device moves out of the range of one cell tower and into another, the network must switch the connection to the new tower without interrupting the call or data session. 'Hard handoffs' involve a brief disconnect, while 'soft handoffs' (common in CDMA) connect to the new tower before disconnecting from the old one.
19
What is 'Baseband' transmission?
Answer:
Using the entire bandwidth of the medium to send a single digital signal.
Baseband transmission uses the entire capacity of the communication medium to transmit a single data signal at a time. It is commonly used in LANs (like Ethernet). In contrast, broadband (or passband) transmission divides the medium into multiple frequency channels to carry different signals at the same time.
20
In the context of network security, what is a 'Sybil Attack'?
Answer:
An attacker creates many fake identities to gain disproportionate influence in a peer-to-peer network.
A Sybil attack occurs when a single malicious actor creates multiple fake nodes or identities in a distributed system. This can be used to subvert reputation systems, rig elections, or disrupt routing in decentralized networks (like blockchains or DHTs) by controlling a large portion of the 'votes' or 'nodes'.