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
31
In the Context of RIP (Routing Information Protocol), what is 'Split Horizon'?
Answer:
A rule that prevents a router from advertising a route back out the same interface it learned it from.
Split Horizon is a loop-prevention mechanism in distance-vector routing protocols. It works by not sending routing information back to the source from which it was received. This prevents two routers from continuously bouncing incorrect routing information back and forth (counting to infinity).
32
In a Content Delivery Network (CDN), what is 'Edge Computing'?
Answer:
Running applications and processing data closer to the end-user at the network periphery.
Edge computing involves moving computation and data storage away from central data centers and closer to the 'edge' of the network—near the users. This reduces latency for applications like video streaming, gaming, and IoT by processing data locally rather than sending it back and forth to a distant cloud server.
33
In wireless networking (802.11), what does the 'NAV' (Network Allocation Vector) represent?
Answer:
A virtual carrier sensing mechanism that tracks the remaining time the medium will be busy.
The Network Allocation Vector (NAV) is used in the CSMA/CA protocol for 802.11 wireless networks. It is a timer updated by information in the headers of frames sent by other stations. It allows a station to know how long the medium will be reserved for a transmission sequence (like an RTS/CTS exchange), even if the station cannot 'hear' the actual data transmission.
34
What is the function of 'Gratuitous ARP'?
Answer:
To update the ARP tables of other hosts when a host's IP or MAC address changes.
A Gratuitous ARP is an ARP Response that was not prompted by an ARP Request. It is broadcasted by a host to inform other hosts on the network about its IP-to-MAC mapping. This is commonly used for duplicate IP detection and for updating ARP caches on other devices when a cluster fails over or an interface is changed.
35
In the context of TCP Congestion Control, what is the specific purpose of the 'Fast Recovery' algorithm?
Answer:
To prevent the congestion window from dropping to 1 MSS after receiving three duplicate ACKs.
Fast Recovery is an optimization in TCP (specifically TCP Reno) that allows the sender to maintain a higher throughput after a packet loss is detected via triple duplicate ACKs. Instead of dropping the congestion window to 1 Maximum Segment Size (MSS) and entering Slow Start, it sets the window to a value related to the current threshold, assuming the network is still capable of delivering segments since ACKs are still arriving.
36
What is the purpose of the 'Pseudo-header' used in TCP and UDP checksum calculations?
Answer:
To protect against misrouted packets by including IP addresses and protocol information in the checksum.
The pseudo-header contains fields from the IP header (Source/Destination IP, Protocol, and Length). By including these in the transport-layer checksum, TCP and UDP can detect if a packet has been delivered to the wrong destination or has been corrupted in a way that the IP header alone might not catch.
37
Which field in the IPv4 header is used to prevent packets from looping infinitely?
Answer:
Time to Live (TTL)
The TTL field is an 8-bit value that is decremented by every router that processes the packet. When the TTL reaches zero, the packet is discarded, and an ICMP 'Time Exceeded' message is usually sent to the source. This prevents packets from circulating indefinitely in the event of a routing loop.
38
What is 'Traffic Shaping'?
Answer:
Delaying some packets to bring them into compliance with a desired traffic profile.
Traffic shaping (also known as packet shaping) is a bandwidth management technique that delays certain types of packets to optimize or guarantee performance, improve latency, or increase usable bandwidth for some kinds of packets by delaying others. It is often used to ensure that a bursty connection doesn't exceed a committed rate.
39
What is 'Jitter' in network communications?
Answer:
The variation in packet arrival times (latency variance).
Jitter refers to the inconsistency in latency over time. In real-time applications like VoIP or video conferencing, high jitter can lead to choppy audio or distorted video because the receiver cannot smoothly reassemble the stream if packets arrive at highly irregular intervals.
40
Which layer of the OSI model does the 'TLS' (Transport Layer Security) protocol typically operate in, even though it's often used by applications?
Answer:
Transport Layer / Session Layer
TLS is designed to secure communications over the Transport Layer (TCP). In the OSI model, it is generally considered to span the Transport, Session, and Presentation layers. It provides encryption, authentication, and data integrity for application protocols like HTTP, SMTP, and FTP.