PPPoE (Point-to-Point Protocol over Ethernet) relies on Ethernet broadcast and discovery mechanisms. It uses a discovery stage (PPPoE Active Discovery Initiation – PADI) which is sent as a broadcast. Therefore, PPPoE only works within the same Layer 2 broadcast domain.
If a router (Layer 3 device) exists between the client and PPPoE server, it breaks the Layer 2 broadcast domain, making it impossible for the client to reach the server.
A.✘False – Routers break the broadcast domain; PPPoE will fail.
B.✔True – PPPoE requires L2 adjacency.
Extract from Official MTCNA Course Material – PPPoE Concepts:
“PPPoE operates only over Ethernet broadcast domains. If routed, PADI packets will not reach the PPPoE server.”
Extract from René Meneses MTCNA Study Guide – PPPoE:
“PPPoE discovery is broadcast-based and does not traverse routers.”
Extract from MikroTik Wiki – PPPoE Limitations:
“PPPoE cannot function over routed networks. Server and client must be in the same broadcast domain.”
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