I created some azure network infrastructure to connect 3 different appservices under the same domain. After creation of public IP address added it to DNS (outside of azure).
For like one or maybe two months it was working perfectly fine, but after that ip changed to dash (-). I provided screenshot below to show that.
Configuration for this Public IP address is:
IP address assignment - Dynamic;
Idle timeout (minutes) - 4;
And its only associated to gateway.
I have zero ideas why it happened or how I can get ip back to it. It happened a second time, first time I just recreated public IP and change DNS setting, but its annoing to do it every 1-2 month. Maybe someone know why it happens?
Dynamic IP addresses in Azure are not guaranteed to be retained after the idle timeout threshold is reached. They will be returned to the broader IP pool at some point after this idle period.
If you have a requirement to maintain the same IP address regardless of inactivity, you'll need to configure your resource with the Static IP address assignment setting. Alternatively, you can change your architecture to leverage Azure DNS as your domain's nameservers and create an A record that's an alias to the resource itself, which will dynamically resolve to whatever IP address is assigned to the resource at the time of the request.
See also: Public IP addresses in Azure - Azure Virtual Network documentation