Computer Networks

WiMAX (Worldwide Interoperability for Microwave Access) is a broadband wireless technology designed for long-range, non-line-of-sight operation. Unlike Wi-Fi which is short-range, WiMAX can cover several kilometers and doesn't require line-of-sight between antenna and receiver, making it suitable for last-mile broadband replacement for DSL.

Full-duplex Ethernet allows simultaneous transmission and reception on both ends of the link. In full-duplex mode, collisions are physically impossible because each device has separate transmit and receive circuits. The switch and workstation can both send and receive at the same time without contention. Half-duplex uses CSMA/CD to detect collisions, but full-duplex disables this mechanism entirely.

WiMAX (Worldwide Interoperability for Microwave Access) is a broadband wireless technology designed to provide non-line-of-sight connectivity with speeds comparable to DSL. Unlike Wi-Fi which is short-range, or Satellite which has high latency, WiMAX offers metropolitan-area coverage with DSL-like speeds. Metro Ethernet requires physical cables, not a wireless solution.

Traditional inter-VLAN routing requires a physical router interface connected to a separate switch port for each VLAN. In contrast, router-on-a-stick uses a single physical router port configured with multiple logical subinterfaces, each corresponding to a different VLAN, connected to a trunk port on the switch.

The 'last mile' refers to the final leg of the telecommunications network from the provider's central office to the customer premises. This includes the local loop (the physical copper/fiber lines). The demarcation point is where provider responsibility ends, typically at the customer's building entrance.

A supernet is a summarized route that combines multiple contiguous classful networks into a single larger network block. This reduces routing table size. It is not a default route (0.0.0.0/0), does not mix public/private addresses, and represents contiguous networks.

A rollover cable (also called a console cable) is used to connect a PC terminal to a router's console port. The cable pins are reversed at one end (pin 1 connects to pin 8, pin 2 to pin 7, etc.), which is required for the console connection. Straight-through cables connect different devices, while crossover cables connect similar devices.

An Autonomous System (AS) is defined as a collection of networks under a single administrative entity that presents a common routing policy to the internet. This is the standard definition used in BGP and inter-domain routing. AS numbers identify these systems globally.

Telnet transmits all data (including usernames and passwords) in clear text over the network, making it vulnerable to eavesdropping and packet sniffing attacks. SSH encrypts the entire session, providing confidentiality and integrity. Telnet is widely available (option A is wrong), uses minimal bandwidth (option C is wrong), and does support authentication (option D is wrong - you authenticate with username/password, just not securely). The lack of encryption is Telnet's fundamental security weakness.

Data link layer protocols like PPP (Point-to-Point Protocol) and HDLC (High-Level Data Link Control) define how data is encapsulated into frames for transmission across WAN links. They handle framing, error detection, and authentication. Option A is incorrect because ISDN is circuit-switched but ATM is a cell-switched technology. Option C describes circuit-switching, not packet-switching. Option D is wrong because Frame Relay switches are service provider equipment, not customer premises equipment maintained by local administrators.

The Cisco IOS image file is stored in flash memory. Before upgrading to a newer or larger IOS version, an administrator must verify that the router has sufficient flash memory capacity to hold the new image.

Excessive broadcasts typically occur at Layer 2 (Data Link layer) due to network design issues, spanning tree problems, loops, or malfunctioning devices. Broadcasts propagate through the broadcast domain at Layer 2. Physical layer issues (option A) usually cause connectivity problems or errors, not excessive broadcasts. Network layer (option C) deals with routing, and Transport layer (option D) handles end-to-end communication like TCP/UDP.

An Optical Time Domain Reflectometer (OTDR) is the specialized device used to test fiber optic installations. It sends light pulses into the fiber and analyzes the backscattered light to detect faults, measure fiber length, identify bends or breaks, and assess overall signal integrity and performance characteristics. TDR is for copper cables, multimeters measure electrical signals, and light injector is not a standard testing tool.

Circuit-switched WAN implementations require establishing a dedicated physical circuit through the network before any data transfer can begin. This call setup time creates a delay before communication can start, which is inefficient for bursty data traffic compared to packet-switched networks. The circuit must be fully established end-to-end first, then data flows, then the circuit is torn down - this setup/teardown overhead is the key drawback. Voice traffic is actually well-suited to circuit switching.