An enterprise core network routes traffic using several dynamic interior and exterior rout… — CompTIA Network+

An enterprise core network routes traffic using several dynamic interior and exterior routing protocols alongside static routing rules. Match each routing protocol or forwarding evaluation rule on the left with its exact operational metric or selection characteristic on the right.

Internal BGP (iBGP)Carries a default administrative distance of 200 and preserves AS_PATH attributes across internal peers without prepending its local AS.
OSPFv2Uses a link-state metric derived from reference bandwidth over interface bandwidth ( $Cost = \frac{\text{Reference Bandwidth}}{\text{Interface Bandwidth}}$ ) with a default administrative distance of 110.
Internal EIGRPUses a composite metric of minimum bandwidth and cumulative delay by default ( $K_1=1, K_3=1$ ) with a default administrative distance of 90.
Longest Prefix MatchPrecedes all administrative distance and protocol metric comparisons during routing table lookup and packet forwarding.

Answer

Internal BGP matches with default AD 200 and AS_PATH preservation; OSPFv2 matches with bandwidth cost metric and AD 110; Internal EIGRP matches with composite bandwidth/delay metric and AD 90; Longest Prefix Match matches with overriding all AD and metric evaluations during lookup.

Each protocol and lookup rule follows strict architectural standards: iBGP operates at AD 200, OSPF calculates cost based on bandwidth with AD 110, EIGRP uses composite metrics with AD 90, and Longest Prefix Match serves as the primary route selection criterion before AD or metrics are evaluated.

Step-by-Step Solution

Analyze Longest Prefix Match hierarchy

Identify that prefix mask length (/28 vs /24) takes absolute priority over Administrative Distance and routing metrics during packet forwarding.

Longest Prefix Match is evaluated first before comparing Administrative Distance among competing routes.

Evaluate internal BGP Administrative Distance and AS_PATH propagation

Associate iBGP with AD 200 and unchanged AS_PATH propagation.

iBGP routes have an AD of 200 (compared to eBGP's AD of 20) to ensure local IGP routes take precedence unless explicitly configured otherwise.

Differentiate IGP metrics and Administrative Distances (OSPF vs EIGRP)

Match OSPF to inverse bandwidth cost formula with AD 110, and EIGRP to composite vector metric (minimum bandwidth + cumulative delay) with AD 90.

OSPF evaluates link costs calculated from bandwidth, whereas EIGRP uses vector composite metrics.

Key Concept

Routing table path selection order, administrative distance hierarchy, and dynamic protocol metric calculation mechanisms.

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