Computer Networks

Fiber Distributed Data Interface (FDDI) provides a 100 Mbit/s optical standard for data transmission in local area network that can extend in range up to 200 kilometers (120 mi). Although FDDI logical topology is a ring-based token network, it does not use the IEEE 802.5 token ring protocol as its basis; instead, its protocol is derived from the IEEE 802.4 token bus timed token protocol.

The network layer provides the functional and procedural means of transferring variable length data sequences from a source host on one network to a destination host on a different network (in contrast to the data link layer which connects hosts within the same network), while maintaining the quality of service requested by the transport layer. Since, in broadcast networks, the packets have to be sent to all the hosts, this layer is not mandatory.

Duplex mismatch occurs when one end is autonegotiating (switch) and defaults to half-duplex while the other end (PC) is hardcoded to full-duplex. This causes late collisions and packet loss on the full-duplex side, leading to slow and intermittent connectivity. The solution is to ensure both ends autonegotiate or both are manually configured to the same duplex setting.

When creating network documentation, you should first record comprehensive information about all discovered devices across the entire network, including remote locations. Then, transfer this information from the network configuration table to build out the topology diagram components. Option A is incorrect because documentation should cover the entire network, not just campus. Option D incorrectly limits the transfer to only Layer 2/3 information when all relevant details should be documented. Option E unnecessarily restricts documentation to peak utilization periods.

A WAN switch device is a multiport internetworking device that switches various WAN traffic types such as Frame Relay, ATM, or X.25 across the wide area network. It operates at the data link and network layers to route and switch traffic between different WAN technologies and locations. Option B describes a router's WAN access function. Option C describes a CSU/DSU device. Option D describes a modem's function.

The show interface command output primarily reveals issues at the Data Link layer (Layer 2) of the OSI model, as it displays information about interface status, CRC errors, framing errors, and collisions - all Layer 2 phenomena. Physical layer issues would show as line down or excessive carrier transitions. Network layer problems would be visible in routing tables and IP-specific commands. Transport and Application layer issues require different diagnostic commands.

Wireless access points use CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to handle multiple users and distributed access. Unlike CSMA/CD used in wired Ethernet, CSMA/CA avoids collisions through acknowledgments and random backoff timers, since wireless devices cannot detect collisions during transmission. Token passing is used in Token Ring networks. Polling is a controlled access method but not the standard for Wi-Fi. CSMA/CD cannot work in wireless because stations cannot detect collisions while transmitting.

When both switch ends are set to auto mode for trunk negotiation, no trunk will form because neither side actively initiates the negotiation. At least one end must be set to desirable or trunk mode for successful trunk establishment. Option A is incorrect because Cisco switches support both ISL and 802.1Q trunking protocols. Option C is incorrect because VLAN 5 would not block trunk formation. Option D is incorrect because mismatched native VLANs cause problems but don't prevent trunk formation itself.

Dial-up uses telephone service.

(Metropolitan Area Network) A communications network that covers a geographic area such as a town, city or suburb. So this choice is correct.

After a collision in CSMA/CD, hosts wait for their backoff period to expire. Once the backoff time elapses, they must return to listen-before-transmit mode to check if the channel is idle before attempting retransmission. This prevents immediate re-collision. Hosts do not have priority - they compete fairly for channel access.

CSU/DSU (Channel Service Unit/Data Service Unit) is the required device for digital lines like T1, E1, or T3. It connects customer equipment (router) to the local loop, performing signal conditioning, timing, and line termination functions that analog modems cannot provide for digital circuits.

A modular switch is characterized by flexible physical characteristics - it typically has a chassis with multiple slots allowing line cards or modules to be added, removed, or upgraded as needed. This provides scalability and investment protection. It's not defined by being slim-line or having fixed characteristics.

Metro Ethernet provides high-bandwidth packet-switched WAN connectivity that can integrate data, voice, and video on the same physical infrastructure. Unlike TDM, ISDN, or PSTN which are circuit-switched or limited in bandwidth, Metro Ethernet offers scalable, cost-effective, converged services delivery.