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300-410 Practice Question: Examine the following partial configuration on a…
Examine the following partial configuration on a PE router:
interface GigabitEthernet0/1 ip vrf forwarding CUSTOMER-A ip address 10.1.1.1 255.255.255.252
!
router bgp 65000 neighbor 192.168.1.1 remote-as 65000 neighbor 192.168.1.1 update-source Loopback0
! address-family ipv4 vrf CUSTOMER-A
neighbor 10.1.1.2 remote-as 65001 neighbor 10.1.1.2 activate
exit-address-family
What is the effect of this configuration?
⚠ Common exam trap
300-410 often tests the confusion between global BGP and VRF address-family configuration, where candidates might think the neighbor must be configured globally or that update-source is mandatory for eBGP.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The eBGP session between PE and CE will be established successfully.
The configuration shows that the eBGP session between the PE and CE router will be established successfully because the neighbor is configured under the VRF address family with the correct remote-as (65001) and activated. The PE router's interface is in VRF CUSTOMER-A with IP 10.1.1.1/30, and the CE neighbor is 10.1.1.2, which is reachable. The global BGP neighbor 192.168.1.1 is for iBGP and does not affect the VRF session.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The eBGP session between PE and CE will be established successfully.
Why this is correct
The VRF is defined, the interface is in the VRF, and the BGP neighbor is correctly configured under the VRF address-family. The neighbor IP is on the same subnet, so the eBGP session should come up.
- ✗
The BGP session will fail because the neighbor must be configured under the global BGP process.
Why it's wrong here
Cisco IOS permits VRF neighbours to be defined directly under the address-family ipv4 vrf block, so the session establishes normally. It is tempting because global BGP process configuration is required for non-VRF peers, but that rule does not extend to VRF address-family neighbours.
- ✗
The BGP session will fail because the neighbor remote-as must match the AS of the PE router.
Why it's wrong here
The remote-as 65001 correctly identifies the customer as an external peer; eBGP neighbours are expected to use a different AS from the local router. It is tempting to assume AS matching is required, but that applies to iBGP sessions, not to eBGP VRF peers.
- ✗
The BGP session will fail because the update-source is not specified for the VRF neighbor.
Why it's wrong here
The neighbour address 10.1.1.2 sits on the directly connected GigabitEthernet0/1 subnet, so IOS uses that interface as the source by default. It is tempting because update-source is mandatory for loopback-based iBGP sessions, but it is unnecessary for directly connected eBGP peers.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.