Answer: Data rate is the number of bits transmitted per second (bps) over a communication channel.
Answer: OSPF (Open Shortest Path First) [Also acceptable: RIP, IS-IS]
Answer: TCP
Answer: Provides secure communication over a public network through encryption.
Answer: n(n-1)/2
Answer: 18.4% or 1/(2e)
Answer: Multicasting.
Answer: Piggybacking
Answer: DNS (Domain Name System) translates domain names into IP addresses.
Answer: Hamming Code
Answer: ARP (Address Resolution Protocol)
Answer: Transport Layer
| Circuit Switching | Packet Switching |
|---|---|
| Dedicated path established | No dedicated path |
| Resources reserved | Resources shared |
| Fixed delay | Variable delay |
| Suitable for voice calls | Suitable for data communication |
| Example: Telephone network | Example: Internet |
Circuit Switching advantages: guaranteed bandwidth, predictable delay. Packet Switching advantages: better bandwidth utilization, more efficient.
Definition: Every node directly connected to every other node. Number of links = n(n-1)/2. Advantages: highly reliable, no congestion, easy fault isolation, high security. Disadvantages: expensive, complex wiring. Applications: military, WAN backbone.
Independent ACK: each frame acknowledged separately → precise error detection. Cumulative ACK: one ACK confirms multiple frames → reduces overhead. When both windows =1, Go-Back-N behaves like Stop-and-Wait ARQ.
CRC (Cyclic Redundancy Check): binary division, remainder appended. Example: Data=1101011011, generator=10011 → append 4 zeros, divide → remainder=1110 → transmitted frame: 1101011011 1110. Detects burst errors, highly reliable.
Transport services: Connection-oriented (TCP: reliable, ordered) and Connectionless (UDP: fast, no guarantee). Segment: PDU of Transport Layer. Congestion: network traffic exceeds resources → delay & packet loss.
Bit stuffing: after five consecutive 1s, a 0 is inserted. Flag pattern: 01111110. Example: 1111101111110 → after stuffing: 1111100 11111010. Receiver removes stuffed bits. Prevents false flag detection, used in HDLC, PPP.
Comparison: transmitted: 1110011011, received: 1100011011 → bit position 3 differs. Error position: 3rd bit. Corrected code = 1110011011. Single-bit error detected & corrected via Hamming code.
Physical addressing (MAC), frame delimiting, access control (CSMA/CD, CSMA/CA), error detection (CRC), collision handling, media access management. Ensures efficient shared medium access.
Based on Bellman-Ford; routers exchange tables with neighbors. Example: A–1–B–2–C, A–4–C. Path A→B→C cost=3 (best). Advantages: simple, low complexity. Disadvantages: slow convergence, count-to-infinity.
Routers continuously increase hop count for failed route (2→3→4...). Solutions: Split Horizon, Poison Reverse, Triggered Updates, Hold-down Timer, Maximum Hop Count.
Process-to-process delivery, segmentation & reassembly, flow control, error control, multiplexing, connection management, congestion control. Ensures reliable end-to-end communication.
Traffic shaping: packets stored in bucket, leaks at constant rate. Excess packets discarded. Smooth traffic, reduces congestion, simple but does not support bursts.
Preventive: Retransmission policy, Window policy, Acknowledgement policy, Discard policy, Admission policy. Prevents congestion before occurrence, improves QoS.
DNS: domain → IP translation, distributed hierarchical database. FTP: file transfer, ports 20 (data) & 21 (control). Firewall: monitors/filters traffic; packet filtering, stateful, proxy. TELNET: remote login (port 23), insecure plain text.
Total addresses: 65536. Group1 (64×256): 16384 addresses → 190.100.0.0 – 190.100.63.255. Group2 (128×128): 16384 → 190.100.64.0 – 190.100.127.255. Group3 (128×64): 8192 → 190.100.128.0 – 190.100.159.255. Remaining: 65536 – (16384+16384+8192) = 24576 addresses.
Longest prefix match: 131.23.151.76 falls under 131.22.0.0/15 (covers 131.22.0.0 – 131.23.255.255) → Interface = 1.
Subnetting: dividing large network into smaller subnetworks → better management, reduced broadcast. Supernetting: combining multiple networks into one → reduces routing table size, efficient aggregation.
✔ Complete coverage of MAKAUT Computer Networks (ECC602/PCC-CS602) 2024–25 – all groups.
✔ Includes data rate, intradomain routing, VPN, mesh topology, CRC, bit stuffing, Hamming code, distance vector, count-to-infinity, leaky bucket, open loop control, DNS, FTP, firewall, CIDR, subnetting, supernetting, and ISP allocation.
✔ Answers structured for 1, 5, and 15-mark questions with clear headings & exam-style presentation.