CCIE Enterprise Infrastructure Flashcards

Which Cisco feature enables automatic failover of Layer 3 gateway redundancy using virtual IP and MAC addresses?

Answer: All of the above provide gateway redundancy

HSRP, VRRP, and GLBP all provide first-hop redundancy using virtual IPs; GLBP additionally provides load balancing across multiple routers.

In MPLS, what is the label imposed at the ingress PE router called?

Answer: Transport label

The transport (outer) label is imposed at the ingress PE and used by the MPLS core (P routers) for forwarding decisions.

What is Penultimate Hop Popping (PHP) in MPLS?

Answer: Removing the transport label at the second-to-last hop

PHP removes the outer transport label at the penultimate (second-to-last) hop, reducing processing at the egress PE router.

Which 802.1Q feature allows traffic from multiple VLANs to traverse a single physical link between switches?

Answer: Trunk port

Trunk ports use 802.1Q encapsulation to tag frames with VLAN IDs, allowing multiple VLANs to traverse a single inter-switch link.

In OSPF, what mechanism prevents routing loops by ensuring non-backbone areas communicate only through Area 0?

Answer: Backbone requirement

OSPF requires all non-backbone areas to connect to Area 0 (backbone), which prevents routing loops in multi-area OSPF designs.

Which technology combines multiple physical interfaces into one logical interface for increased bandwidth and redundancy?

Answer: EtherChannel / LACP

EtherChannel (using LACP or PAgP) bundles multiple physical links into one logical link, providing both bandwidth aggregation and redundancy.