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
1
Which of the following is a 'Distance-Vector' routing protocol?
Answer:
RIP
The Routing Information Protocol (RIP) is a classic distance-vector protocol. It works by having each router share its entire routing table with its immediate neighbors at regular intervals. Routers use the Bellman-Ford algorithm to calculate the best path based on the hop count.
2
What is the primary difference between IPv4 and IPv6 header structures regarding fragmentation?
Answer:
IPv4 allows routers to fragment packets, whereas in IPv6, fragmentation is performed only by the source host.
In IPv4, intermediate routers can fragment packets if they exceed the MTU of the next link. In IPv6, routers are not allowed to fragment packets; they simply drop the packet and send an ICMPv6 'Packet Too Big' message back to the source. The source host is then responsible for performing Path MTU Discovery and fragmenting the data using an Extension Header if necessary.
3
What is the purpose of 'Subnetting'?
Answer:
To divide a large network into smaller, more manageable logical segments.
Subnetting allows a network administrator to divide a single large block of IP addresses (like a Class B network) into several smaller networks. This helps reduce broadcast traffic, improves security by isolating network segments, and allows for more efficient use of the assigned IP address space.
4
What is the 'Diameter' of a network in graph theory terms?
Answer:
The maximum number of edges on the shortest path between any two nodes.
In network topology analysis, the diameter is the longest of all shortest paths between any two nodes. A smaller diameter generally implies that the network can communicate more efficiently, as the 'worst-case' distance between any two points is minimized.
5
Which of the following describes the 'Silly Window Syndrome' in TCP?
Answer:
Small increments in window space lead to the transmission of very small data segments.
Silly Window Syndrome occurs when either the sender or the receiver forces the transmission of very small segments (e.g., 1 byte of data in a 40-byte header). This is highly inefficient. It is usually mitigated by Nagle's algorithm on the sender side and Clark's solution on the receiver side, which prevents the receiver from advertising a tiny window.
6
Which mechanism is used in HTTP/2 to allow the server to send resources to the client before the client requests them?
Answer:
Server Push
HTTP/2 Server Push allows a server to speculatively send resources (like CSS or JavaScript files) that it anticipates the client will need. This reduces the number of round trips required to render a page, as the client doesn't have to wait to parse the HTML before requesting secondary assets.
7
What is the 'Three-Way Handshake' in TCP?
Answer:
SYN, SYN-ACK, ACK
The three-way handshake is the process used to establish a TCP connection. The client sends a SYN (Synchronize) packet, the server responds with a SYN-ACK (Synchronize-Acknowledgment), and the client completes the process with an ACK (Acknowledgment). This ensures both sides are ready and have synchronized their initial sequence numbers.
8
In the context of congestion control, what does 'ECN' (Explicit Congestion Notification) allow routers to do?
Answer:
Mark packets to signal congestion to the end hosts without dropping them.
ECN is an extension to the Internet Protocol and TCP that allows end-to-end notification of network congestion without dropping packets. Routers that support ECN can set bits in the IP header to indicate congestion. The receiver then echoes this back to the sender in an ACK, allowing the sender to reduce its transmission rate before packet loss actually occurs.
9
What does the 'Multipath TCP' (MPTCP) extension allow a single connection to do?
Answer:
Transmit data across multiple network paths (e.g., WiFi and LTE) simultaneously.
Multipath TCP (MPTCP) is an effort to allow a single TCP connection to spread its traffic across multiple interfaces or paths. This provides better resource utilization, increased throughput, and improved resilience. For instance, a smartphone could use both its cellular data and WiFi connections simultaneously to download a single file.
10
What is the 'Slow Start' threshold (ssthresh) used for in TCP?
Answer:
To determine when to switch from Slow Start to Congestion Avoidance.
In TCP congestion control, the sender starts in the Slow Start phase, doubling the congestion window every RTT. Once the window size reaches the ssthresh (Slow Start Threshold), the sender switches to the Congestion Avoidance phase, where the window grows linearly to avoid overwhelming the network.