There are some limitations for Azure container instances.
The IP address of a container won't typically change between updates,
but it's not guaranteed to remain the same. As long as the container
group is deployed to the same underlying host, the container group
retains its IP address. Although rare, and while Azure Container
Instances makes every effort to redeploy to the same host, there are
some Azure-internal events that can cause redeployment to a different
host. To mitigate this issue, always use a DNS name label for your
container instances.
Terminated or deleted container groups can't be updated. Once a
container group has stopped (is in the Terminated state) or has been
deleted, the group is deployed as new.
However, It's a rare case that Azure container instances will be redeployed to a different host. Also, if you have a container instance in a VNet, you're unable to directly set a --dns-name-label value and you only could access the instance via its private IP address from the outside world and other container groups. Note: Containers in a group are not discoverable through DNS. They can only be accessed through ‘localhost’, in combination with their exposed ports. You could get more references from More about networking in this blog.
