Exam 400-007 topic 1 question 220 discussion

https://www.cisco.com/c/en/us/td/docs/dcn/whitepapers/migrating-classic-ethernet-to-vxlan-bgp-evpn-white-paper.html

I think it is better to set the right expectation, "non disruptive migration is not supported". then the customer will be ready to engage the host's admin to support if needed.

Considering the VRRP issue noted by others, and having done this several times with both HSRP and VRRP, the customer already knows there will be a potential ARP issue at the endpoint level, so they take that into consideration before changing where the actual SVI will sit. Shutting it down on the old and enabling it on the new will cause short term issues. Knowing it will be an issue to me makes it part of the verification process and the right folks are available and on the call when the change occurs, therefore, there's no outage, you're in a maintenance window and end systems are being verified, you troubleshoot the ones that are having issues.

the same paper as blurain mentions reads: "The practice of changing the FHRP virtual MAC followed by a state change (active-standby) results in the highest probability that connected endpoints relearn the first-hop gateway’s new virtual MAC address. Nonetheless, a possibility remains that some endpoints will not honor the signalization through GARP or have a static MAC entry for the first-hop gateway. These endpoints require manual intervention to flush their ARP cache and hence, we recommend performing this action during a Maintenance Window."

https://www.cisco.com/c/en/us/td/docs/dcn/whitepapers/migrating-classic-ethernet-to-vxlan-bgp-evpn-white-paper.html "Note: Non-disruptive migration is not supported if the existing Classic LAN fabric is using VRRP/VRRPv3 as FHRP protocol. In this case, you must schedule a maintenance window for migrating the default gateway between the legacy network and the greenfield VXLAN EVPN fabric." Considering the above, the next best answer would be B