A city traffic-operations center must identify which OSPF router is summarizing inter-area prefixes versus which one is redistributing an external routing source at the civic core. Which role mapping is correct?

At a city traffic-operations center, role vocabulary must separate area connectivity from external redistribution. An ABR connects one or more OSPF areas (always including a path toward area 0 in a standard design) and can originate Type-3 summary LSAs that describe one area’s prefixes to another. An ASBR redistributes routes from outside OSPF—BGP, another IGP, statics—into OSPF, typically as Type-5 (or Type-7 in an NSSA). The same physical router can be both ABR and ASBR, but the jobs differ: Type-3 summarization versus external injection. That mapping is why the correct answer works for identifying who summarizes inter-area prefixes versus who redistributes an external source at the civic core. Claiming an ASBR only connects two OSPF areas and never redistributes swaps ABR and ASBR definitions. Saying an internal router always originates Type-5 externals for every area is wrong because internal routers are neither ABR nor ASBR by definition and do not originate Type-5s. Asserting a backbone router cannot be an ABR when it attaches to area 0 and another area contradicts the ABR definition—attachment to area 0 plus another area is exactly what makes a router an ABR. Exam caveat: ABR is about area membership and Type-3/Type-4 roles; ASBR is about redistribution; do not equate “backbone router” with “cannot be ABR.” Operational check: use show ip ospf border-routers and show ip ospf database to identify ABR-generated Type-3/Type-4 LSAs versus ASBR-originated Type-5/Type-7; map each civic prefix’s LSA type to the responsible role before changing redistribution or summarization.