Cisco Certified Support Technician (CCST) NetworkingIP ConnectivityMedium
A network administrator is configuring EIGRP on a router and wants to ensure that specific interfaces participate in the EIGRP routing process, while other interfaces (e.g., connecting to the internet) do not send or receive EIGRP updates. Which EIGRP configuration feature should be used to achieve this?
- ANo auto-summary
- BVariance
- CPassive-interface
- DStub routing
Show answer & explanationAnswer & explanation
Correct answer: C. Passive-interface
The `passive-interface` command in EIGRP (and other routing protocols like OSPF and RIP) prevents routing updates from being sent out of a specified interface and also prevents the router from forming neighbor adjacencies over that interface. This is crucial for security and efficiency, especially on interfaces connecting to end-user segments or the internet.
Why the other options are wrong
- A. No auto-summary prevents automatic summarization of routes at major network boundaries, unrelated to interface participation.
- B. Variance allows EIGRP to load-balance across unequal-cost paths, which is not about controlling interface participation.
- D. Stub routing is a feature for EIGRP to optimize routing in stub networks, not for preventing updates on specific interfaces.
EIGRP Passive-Interface
A configuration command in EIGRP (and other routing protocols) that disables the sending and receiving of routing updates on a specified interface, while still advertising the network connected to it.
- Prevents neighbor adjacency formation on the interface.
- Conserves bandwidth and router resources.
- Enhances security by not sending routing updates to untrusted networks.
Memory trick: Passive: Quiet on the network front.