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400-007 · Question #64
400-007 Question #64: Real Exam Question with Answer & Explanation
The correct answer is B: IS-IS. IS-IS is the most restrictive routing protocol for a multipoint IPsec VPN deployment because it cannot run natively over tunnel interfaces, limiting scalability to 500+ sites.
Question
A customer asks you to perform a high level review of their upcoming WAN refresh for remote sites. The review is specially focused on their retail store operations consisting of 500+ locations connected via mutlipoint IPsec VPN solution. Which routing protocol would be valid but would also be the most restrictive for the expansion of this deployment model?
Options
- AEIGRP
- BIS-IS
- COSPF
- DBGP
Explanation
IS-IS is the most restrictive routing protocol for a multipoint IPsec VPN deployment because it cannot run natively over tunnel interfaces, limiting scalability to 500+ sites.
Common mistakes.
- A. EIGRP is fully supported over DMVPN and multipoint IPsec tunnel interfaces and scales well with spoke-to-hub deployments using split-horizon tuning.
- C. OSPF supports multiple network types including point-to-multipoint, which maps directly to hub-and-spoke IPsec VPN topologies, making it a common and valid choice.
- D. BGP is the most scalable option for large-scale VPN deployments and is natively used in many MPLS and IPsec overlay designs with no tunnel interface restrictions.
Concept tested. Routing protocol suitability over IPsec tunnel interfaces
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