Networks - 2

For M-ary PSK modulation, the baud rate equals data rate divided by log2(M). With 8-level PSK, log2(8) = 3, so 9600 bps / 3 = 3200 baud. The answer correctly calculates the modulation rate.

The transport layer (Layer 4) provides end-to-end connectivity between hosts, handling reliable data delivery, flow control, and error recovery. The network layer only handles hop-to-hop routing.

For a 9-bit frame with bit error probability 0.001, the probability of NO errors is (1-0.001)^9 ≈ 0.991. Therefore, residual error rate (probability of at least one error) is 1 - 0.991 = 0.009.

Hamming distance counts positions where corresponding bits differ. 001111 vs 000111 (padding 211 to 3 bits) differ only in position 3 from the left. Comparing full strings: 001111 vs 000211 gives distance 3 in binary positions.

Residual error rate is the probability that errors escape detection despite error detection mechanisms. Option B correctly defines this as undetected errors, while C describes detected errors (detection rate, not residual).

Class A: 2^7 - 2 = 126 IDs (first and last reserved), Class B: 2^14 - 16 = 16,382 IDs, Class C: 2^21 - 256 = 2,097,088 IDs. However, the question asks how many CAN exist - all classes combined: 126 + 16,382 + 2,097,088 = 2,113,596.

Each character requires 7 data bits + 1 parity + 1 start + 1 stop = 10 bits total. At 2400 bps: 2400 / 10 = 240 characters per second. The overhead bits reduce effective throughput.

FDDI (Fiber Distributed Data Interface) is a token-passing ring network standard operating at 100 Mbps over fiber optic cable. Its dual-ring architecture provides redundancy and high reliability for campus backbones.

In Ethernet CSMA/CD, when a collision is detected, the transmitting station sends a jam signal to ensure all stations recognize the collision. This forces a backoff period before retransmission attempts.

Wide Area Networks operate over long distances using various transmission media. Telephone lines (leased lines), microwave links, and satellite communications are all common WAN backbone technologies.

In Ethernet LAN using CSMA/CD protocol, only one pair of stations can transmit data at any given time to avoid collisions. When one station is transmitting, all others must listen.

WAN connects devices over large geographical areas using communication satellites and telephone lines. Unlike LAN which covers small areas, WAN spans countries or continents.

X.25 Level 2 (LAPB) operates at the data link layer, not the network layer. The network layer includes protocols like IP and X.25 PLP.

Non-polling systems allow nodes to access the communication medium without explicit permission from a master node. TDMA uses time slots, and carrier sense systems check the medium before transmitting, making them non-polling.

LAN connects computers within a small geographical area like a building or campus without using telephone lines. It's designed for local resource sharing.

In EIA standards like RS-232, RS stands for Recommended Standard. These are voluntary industry standards for electronic equipment compatibility.

LANs enable microcomputer users in a local area to share resources like data, software, and hardware devices. This is the primary purpose of local area networking.

Half-duplex mode allows data transmission in both directions, but not at the same time. Devices take turns transmitting and receiving, like walkie-talkies.

Terminals serve multiple functions in organizational systems: collecting data from physical systems, presenting information to managers, and communicating management decisions back to physical systems for execution.

Computer communication predominantly uses serial transmission because it's more cost-effective over long distances and avoids synchronization issues that parallel transmission faces.

Real-time systems must process data with minimal delay to respond to events as they occur. Offline batch processing introduces delays, and multiple CPUs are not strictly required.

DDS (Digital Data Service) provides digital communication, while DDD and WATS are analog telephone services. DDT is not a communication service at all.

Modems are used to connect to wide area networks (WAN) or the internet through telephone lines, not for local area networks. LANs connect devices like computers, printers, and cables within a limited physical area like a building or campus.