Recommended
Practice
1. In which scenario would you most likely use CIDR notation instead of traditional classful addressing?
easy
Solution
Step 1: Understand classful addressing limitations
Classful addressing allocates IP blocks in fixed sizes (Class A, B, C), often wasting many IP addresses.Step 2: Recognize CIDR's flexibility
CIDR allows variable-length subnet masks, enabling allocation of IP blocks tailored to network size, reducing waste.Step 3: Evaluate options
When you need to allocate IP addresses in fixed blocks of Class A, B, or C sizes describes classful allocation, not CIDR. When you want to separate the network and host portions strictly by the first octet is about classful fixed boundaries. When you want to assign IP addresses only within Class C networks restricts to Class C, which CIDR overcomes.Final Answer:
Option A -> Option AQuick Check:
CIDR is used for efficient IP allocation across variable network sizes [OK]
Hint: CIDR = flexible IP blocks, classful = fixed blocks
Common Mistakes:
- Believing CIDR only applies to Class C networks
- Thinking CIDR is just a different notation without functional difference
- Assuming classful addressing is still standard for IP allocation
2. In which scenario is the IP Hash load balancing algorithm most appropriate compared to Round Robin or Least Connections?
easy
Solution
Step 1: Understand IP Hash purpose
IP Hash uses the client's IP address to consistently route requests to the same backend server, enabling session persistence (sticky sessions).Step 2: Why not Round Robin or Least Connections?
Round Robin distributes requests evenly without regard to client identity, so it does not guarantee session persistence. Least Connections balances based on current load but also does not ensure the same client hits the same server.Step 3: Match scenarios to algorithms
When you need to ensure session persistence by routing requests from the same client IP to the same server correctly identifies the scenario where IP Hash is preferred: session persistence. Options A and C describe scenarios better suited for Least Connections or Round Robin. When you want to distribute requests strictly in a cyclic order regardless of client identity describes Round Robin behavior.Final Answer:
Option A -> Option AQuick Check:
IP Hash -> session stickiness; Round Robin -> cyclic distribution; Least Connections -> load-aware balancing.
Hint: IP Hash = sticky sessions by client IP
Common Mistakes:
- Confusing Least Connections with session persistence
- Assuming Round Robin can maintain client affinity
- Believing IP Hash balances load evenly regardless of client IP distribution
3. Trace the sequence of events in TCP congestion control using AIMD when packet loss is detected via triple duplicate ACKs.
easy
Solution
Step 1: Identify AIMD response to triple duplicate ACKs
On triple duplicate ACKs, TCP performs fast retransmit and fast recovery, cutting congestion window to half.Step 2: Understand congestion window growth after loss
After halving, TCP increases congestion window linearly (additive increase) to probe for available bandwidth.Step 3: Differentiate from timeout behavior
Timeout triggers slow start (reset to 1 MSS), not triple duplicate ACKs.Step 4: Reject ignoring loss or stopping sending
Ignoring loss or stopping immediately are incorrect TCP behaviors.Final Answer:
Option C -> Option CQuick Check:
Triple duplicate ACKs -> halve cwnd -> linear increase.
Hint: Triple duplicate ACKs -> fast retransmit + halve cwnd; timeout -> slow start.
Common Mistakes:
- Confusing timeout and triple duplicate ACK loss signals
- Assuming exponential growth continues after loss
- Believing TCP stops sending immediately on loss
4. Why is it generally not advisable to set a fixed Retransmission Timeout (RTO) value in TCP instead of using an adaptive algorithm?
medium
Solution
Step 1: Understand RTO purpose
RTO determines when the sender retransmits unacknowledged segments, ideally matching network delay.Step 2: Analyze fixed vs adaptive RTO
Fixed RTO cannot adapt to changing RTTs, causing retransmissions either too early (wasting bandwidth) or too late (increasing latency).Step 3: Evaluate options
Because fixed RTO values prevent the sender from using sequence numbers effectively is incorrect; sequence number usage is unaffected by RTO. Because fixed RTO values increase the TCP header size, reducing throughput is false; RTO does not affect header size. Because fixed RTO values cause the receiver to drop out-of-order packets more frequently is unrelated to RTO. Because a fixed RTO cannot adjust to varying network delays, leading to either premature retransmissions or long delays correctly identifies the main drawback.Final Answer:
Option D -> Option DQuick Check:
Adaptive RTO improves efficiency by matching network conditions.
Hint: Adaptive RTO matches RTT; fixed RTO causes inefficiency.
Common Mistakes:
- Believing fixed RTO affects TCP header size
- Confusing RTO with receiver packet handling
- Assuming RTO impacts sequence number usage
5. Which of the following statements about UDP is INCORRECT?
medium
Solution
Step 1: Review UDP characteristics
UDP is connectionless, unreliable, and does not guarantee delivery or order.Step 2: Analyze congestion control
UDP does not implement congestion control; it sends packets without adjusting to network conditions.Step 3: Evaluate options
UDP provides built-in congestion control to avoid network overload is incorrect because UDP lacks congestion control. Options A, C, and D correctly describe UDP behavior.Final Answer:
Option A -> Option AQuick Check:
UDP is simple and fast but does not manage congestion.
Hint: UDP = no connection, no reliability, no congestion control.
Common Mistakes:
- Assuming UDP has congestion control like TCP
- Believing UDP guarantees packet order
- Confusing connectionless with unreliable