Distributed Queue Dual Bus (DQDB), defined by IEEE 802.6, is a standard primarily intended for which type of network?
-
ALAN
-
BMAN
-
CWAN
-
DWireless LAN
-
ELAN and MAN
Answer
Correct Answer: MAN
Explanation
Introduction / Context: DQDB (Distributed Queue Dual Bus) was developed to support metropolitan-scale networks with shared medium access and quality of service considerations across city-wide areas.
Given Data / Assumptions:
- Standard: IEEE 802.6.
- Topology: dual unidirectional buses.
- Scope: metropolitan coverage.
Concept / Approach: MANs bridge the gap between LAN (local building/campus) and WAN (long haul). DQDB’s dual-bus design and distributed queueing aim to coordinate access across multiple nodes over metropolitan distances.
Step-by-Step Solution:
1) Recognize IEEE 802 family mappings: 802.3 (LAN Ethernet), 802.11 (WLAN), 802.6 (MAN DQDB).2) Match DQDB to MAN characteristics (scale, access method).3) Select the MAN option accordingly.Verification / Alternative check: Historical references consistently list DQDB under metropolitan technologies, not LAN/WAN categories.
Why Other Options Are Wrong:
LAN and Wireless LAN target smaller geographic areas.WAN spans much larger, carrier-grade distances and technologies (e.g., MPLS, SDH), distinct from DQDB's MAN scope.“LAN and MAN” conflates scopes; DQDB is specifically a MAN standard.Common Pitfalls: Assuming any IEEE 802 technology is LAN-only; overlooking the MAN category.
Final Answer: MAN.