350-401 · Question #90
350-401 Question #90: Real Exam Question with Answer & Explanation
The correct answer is A: ETR. LISP EID-to-RLOC Mapping Publication An Egress Tunnel Router (ETR) is responsible for registering and publishing EID-to-RLOC mappings for its site by sending Map-Register messages to the Map Server, making it the authoritative source for its site's endpoint reachability informati
Question
Which LISP device is responsible for publishing EID-to-RLOC mappings for a site?
Options
- AETR
- BMS
- CITR
- DMR
Explanation
LISP EID-to-RLOC Mapping Publication
An Egress Tunnel Router (ETR) is responsible for registering and publishing EID-to-RLOC mappings for its site by sending Map-Register messages to the Map Server, making it the authoritative source for its site's endpoint reachability information. The Map Server (MS) is incorrect because it receives and stores the mappings from ETRs rather than publishing them - it acts as the database, not the publisher. The ITR (Ingress Tunnel Router) is also incorrect, as it consumes mappings by sending Map-Request messages to resolve destinations, while the MR (Map Resolver) simply forwards those Map-Requests to the appropriate Map Server on behalf of the ITR.
💡 Memory Tip: Think of it this way - ETR = Exports the mappings (publishes/registers), while ITR = Imports the mappings (looks them up). The "E" in ETR can remind you of "Expose," as in exposing your site's EIDs to the network.
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