CCIE CCIE Enterprise Infrastructure 3 — Questions and Answers
Question 1: Which Cisco feature enables automatic failover of Layer 3 gateway redundancy using virtual IP and MAC addresses?
- VRRP
- HSRP
- GLBP
- All of the above provide gateway redundancy (Correct answer)
Correct 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.
Question 2: In MPLS, what is the label imposed at the ingress PE router called?
- Transport label (Correct answer)
- VPN label
- EXP label
- Penultimate label
Correct answer: Transport label
The transport (outer) label is imposed at the ingress PE and used by the MPLS core (P routers) for forwarding decisions.
Question 3: What is Penultimate Hop Popping (PHP) in MPLS?
- Adding a label at the last P router
- Removing the transport label at the second-to-last hop (Correct answer)
- Swapping labels at the egress PE
- Distributing labels via LDP
Correct 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.
Question 4: Which 802.1Q feature allows traffic from multiple VLANs to traverse a single physical link between switches?
- Port channel
- Trunk port (Correct answer)
- Access port
- Routed port
Correct 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.
Question 5: In OSPF, what mechanism prevents routing loops by ensuring non-backbone areas communicate only through Area 0?
- SPF algorithm
- Backbone requirement (Correct answer)
- DR/BDR election
- LSA flooding
Correct answer: Backbone requirement
OSPF requires all non-backbone areas to connect to Area 0 (backbone), which prevents routing loops in multi-area OSPF designs.
Question 6: Which technology combines multiple physical interfaces into one logical interface for increased bandwidth and redundancy?
- EtherChannel / LACP (Correct answer)
- HSRP
- VSS
- Flex Links
Correct answer: EtherChannel / LACP
EtherChannel (using LACP or PAgP) bundles multiple physical links into one logical link, providing both bandwidth aggregation and redundancy.
CCIE CCIE Enterprise Infrastructure 3
Which Cisco feature enables automatic failover of Layer 3 gateway redundancy using virtual IP and MAC addresses?