Q1: Where are destination and source addresses located in a frame? (2 marks)
Answer: The packet header includes destination and source addresses.
Q2: If a 100 Mbps Ethernet NIC is connected to a hub supporting 10 Mbps, what will be the data rate? (2 marks)
Answer: The hub limits the speed to 10 Mbps. 100 Mbps NIC communicates at hub’s maximum supported speed.
Q3: In connection-oriented networks, which type of connection identifier is used? Give an example. (2 marks)
Answer: ATM uses Virtual Circuit Identifiers (VCI) in connection-oriented networking.
Q4: Network of 6 devices (A–F) on the same packet switch. How does the switch forward a packet from A to E? (3 marks)
Answer: The switch forwards the packet along the path to reach E:
Path: A → D → E
Distance traveled: 4 units (as per switch’s path calculation).
Q5: Network admin needs audio/video service at same data rate. Which ATM quality service applies? Give example. (3 marks)
Answer: Constant Bit Rate (CBR) service for ATM is used for audio/video. Example: AVATAR appliance handling uncompressed bidirectional audio and NTSC video.
Q6: Two satellite locations: 1st has 1 bridge, 2nd has 2 bridges. Which performs faster? Why? (3 marks)
Answer: Location with 2 bridges performs faster because bridges/switches direct traffic only to intended addresses instead of broadcasting, reducing collisions and improving throughput.
Q7: Two sites (A & B) using VPN. Behavior if external user sends packet to A? How is data protected? (5 marks)
Answer:
- Packet is accepted by VPN server, encrypted and encapsulated in standard IP packet (tunneling).
- VPN servers decrypt packet and forward to local network.
- Users see VPN as a dedicated connection; private data is protected over public internet.
Q8: Star Textile network: Ensure network works smoothly if a link fails. Which routing method? (5 marks)
Answer: Distributed routing – each node computes its own routing table and builds connections to neighbors; increases flexibility and performance.
Q9: Shortest path in WAN? (2 marks)
Answer: Dijkstra’s Algorithm is used to compute shortest path from each node to all other nodes.
Q10: Switching techniques in WAN? (2 marks)
Answer: Circuit switching or packet switching. Packet switches move entire packets from one connection to another.
Q11: Names of identifiers used in ATM (2 marks)
Answer: VPI (Virtual Path Identifier) and VCI (Virtual Channel Identifier)
Q12: Ethernet topology? (2 marks)
Answer: Bus topology – all devices share the same communication line.
Q13: Difference between LAN and WAN (2 marks)
Answer:
- LAN: Smaller area (room, floor, building).
- WAN: Covers larger areas (cities, countries), e.g., Internet.
Q14: Why fiber is needed for ATM? (3 marks)
Answer: Fiber provides high-speed, low-latency, and reliable transmission suitable for fixed-length ATM cells.
Q15: Define bridge (3 marks)
Answer: A bridge connects two LAN segments, extending the LAN. It has NICs, CPU, memory, and ROM to forward frames intelligently.
Q16: Ambiguity may cause network failure. How parity bit helps? (5 marks)
Answer: Parity bit detects errors during transmission. If parity check fails, receiver knows data is corrupted and can request retransmission.
Q17: Define default route. How is it different from routing? (5 marks)
Answer:
- Default route: Used when no specific route is found for a destination.
- Routing: Overall process of determining paths for data across network.
Q18: Simplex and full-duplex connections? (2 marks)
Answer:
- Simplex: Data flows in one direction only.
- Full-duplex: Data flows simultaneously in both directions.
Q19: WAN capability to handle many computers? (2 marks)
Answer: WAN uses packet switching and multiple routing paths to connect many computers over large areas.
Q20: Thick Ethernet working structure? (2 marks)
Answer: Uses thick coax cable; NIC connects via AUI cable to transceiver; transceiver converts digital signals to analog on coax. Terminators prevent signal reflection.
Q21: ATM eliminates varying delay of packets? Why? (2 marks)
Answer: Yes, fixed-length cells prevent delay variation caused by variable-length packets.
Q22: ATM design chose cells over packets. Why? (5 marks)
Answer:
- Fixed-length cells simplify memory management.
- Avoid memory fragmentation.
- Easier to guarantee QoS.
- Simplifies hardware and timing requirements.
Q23: Reception is a CPU process. Explain. (5 marks)
Answer: CPU receives packets via NIC, processes headers, checks for errors, and moves data to appropriate application buffer.
Q24: What is 10Base-T?
Answer: Twisted pair Ethernet using max 100 m cable, IEEE 802.3 standard, data rate 10 Mbps.
Q25: What is multicasting?
Answer: Forward frames only to devices programmed to receive a specific multicast address, unlike broadcasting to all.
Q26: FDDI?
Answer: Fiber Distributed Data Interface – ring topology, fiber optic, 100 Mbps, uses two concentric rings.
Q27: Define 802.11 Wireless LAN and CSMA
Answer:
- 802.11: Wireless LAN standard, radio signals at 2.4 GHz, up to 11 Mbps.
- CSMA: Carrier Sense Multiple Access, devices sense medium before transmitting.
Q28: Static vs Dynamic routing (2 marks)
Answer:
- Static: Manual configuration, fixed routes.
- Dynamic: Routers automatically learn paths using protocols (e.g., RIP, OSPF).
Q29: Difference between physical and logical topologies (2 marks)
Answer:
- Physical: Actual wiring layout.
- Logical: Path of data flow, regardless of physical connections.
Q30: Bridges STARTUP vs STEADY state (3 marks)
Answer:
- Startup: Address list empty, forwards unknown frames to all segments.
- Steady: Address list populated, forwards only to correct segment.
Q31: How can switched virtual network (SVC) be established? (3 marks)
Answer: Source requests connection; switches compute path, assign VPI/VCI; destination confirms; SVC established.
Q32: Concept of packet switches (5 marks)
Answer: Each switch forwards entire packets from one connection to another; consists of interfaces, memory, CPU for packet handling.
Q33: Note on weighted graph (5 marks)
Answer: Weighted graph edges have costs; Dijkstra’s algorithm finds shortest path with minimum sum of edge weights.
Q34: Disadvantages of repeaters (3 marks)
Answer: Repeaters amplify errors and collisions; cannot interpret frame formats.
Q35: Difference between cells and packets (5 marks)
Answer:
- Cells: fixed length, simpler memory, easier QoS.
- Packets: variable length, complex memory management, variable delays.