A county courts network team advertises a BGP aggregate for public civic services while still leaking more-specific prefixes for a dual-homed PSAP. Which design element supports that pattern?
Select an answer to reveal the explanation.
Short Explanation
The aggregate is the big city map; the PSAP still needs a few street-level pins. BGP aggregation with selective more-specific advertisement keeps both views.
Full Explanation
The county courts pattern needs a BGP aggregate for public civic services while still advertising selected more-specific prefixes for a dual-homed PSAP. aggregate-address combined with policy that still permits those more-specifics—for example omitting summary-only, or using unsuppress-map / careful suppress logic—supports exactly that: a covering aggregate plus critical PSAP specifics for traffic engineering or dual-homing.
Disabling BGP synchronization is an older IBGP consistency rule about advertising transit routes; it does not create selective more-specifics alongside an aggregate and is not the design element that “forms aggregates after IGP convergence” in the way the distractor implies. Setting PSAP prefixes to OSPF Type-4 is nonsensical for BGP aggregation—Type-4 LSAs locate ASBRs in OSPF and do not make BGP ignore prefixes. EIGRP stub leak-maps on ISP peering routers address EIGRP stub query/leak behavior; they do not replace BGP aggregation toward public civic peers.
Exam caveat: summary-only suppresses more-specifics by default when used; if PSAP specifics must leak, do not blindly enable summary-only, or explicitly unsuppress the needed prefixes. Ensure the aggregate has matching more-specific coverage in the BGP table or the aggregate may not form as expected.
Operational check: on the aggregating courts edge, show bgp ipv4 unicast for the aggregate and the PSAP more-specifics, confirm community/local-pref policy as designed, and verify ISP-facing advertisements with show bgp neighbors advertised-routes. From outside, confirm both the civic aggregate and the selected PSAP specifics are visible while other components remain suppressed.