In the context of live-migrating Virtual Machines (VMs); if taking place over a wide area, there is a chance that the IP address will change between source and destination.

It can be a problem that the user caches the DNS resolution for the original location of the VM, only to find out that the VM is not responding anymore (the original VM was deleted after migration). This problem is mostly true when the user is not connected during the migration, and can therefor not be notified of the change.

While it may be viable to reduce the cache's TTL to very small numbers, I was wondering if there were not a mechanism, e.g. as described in the ipv4/ipv6 RFC, that could make the client automatically evict the DNS cache A/AAAA record entry upon a connection error, and attempt a reconnection.

  • Can you give us more specifics as to what scenarios would cause the ip address assigned to a VM to change due to a live migration? What virtualization platform? Live Migration would seem to imply Hyper-V. While a VM's MAC address can change as a result of a Live Migration, I'm failing to envision a scenario where the ip address would change. – joeqwerty Oct 24 '16 at 19:39
  • Hello, the issue arises when the migration (it could be a VM or even a container; this is not given) occurs over a wide area, e.g. between two data-centers or two distant parts of the same data-center not within the same sub-network. Therefor, the destination and the source will have different IP addresses. – Tama Yoshi Oct 24 '16 at 20:25

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