I have hosted my project in Microsoft Azure by creating Linux VM. I have used Ubuntu 16.04 for my VM. I have created a subdomain there with the name app so that i can access my website as app.example.com.
I have purchased the domain from register.com . I have also pointed my website there & created a A record there.
All are working fine & i can access both my main domain & subdomain like www.example.com & app.example.com but after couple of day the subdomain stop working
According to your description, maybe we can use
nslookup to test domain name.
C:\Users>nslookup jasontest.azurexxxxx.xxx Server: UnKnown Address: 2404:f801:10:12e:fe::2 Non-authoritative answer: Name: jasontest.azurexxxxx.xxx Address: 18.104.22.168
Then we can find the Azure VM's public IP address via Azure portal, if the IP address have changed, we should replace the right public IP address to A record.
By the way, in Azure the public IP address we should use static IP, in this way, public IP address will not change.
Can your browse your website in your Azure VM? use