Custom Domains in Google App Engine

Question

I added a custom domain to point to one of my Google App Engine Projects. It has been approximately 18 hours since I made this change.

How long does it take for DNS changes to propagate. After 18 hours when I hit the domain, I still get "Site can't be reached" on Chrome.

ping: cannot resolve: Unknown host, when I do a ping.

UPDATE: I figured out the issue. I bought the domain uisng Google Domains. It seemed like Google App engine settings, where I added, custom domain was going to update A records in Google Domains for my domain. It didn't. Created A records in Google Domains, and now it works fine. My domain, and subdomain are pointing to a project in Google App engine.

Answer 1

At the bottom of the Add a new custom domain screen from the GAE App's Custom Domains page in the developer console you can see:

DNS changes can require up to 24 hours to take effect

A snapshot of that screen is illustrated at step 5 of the Adding a custom domain for your application procedure.

Side note: maybe it's also worth re-checking the updated settings, it actually happened to me once - I was waiting (in vain) for DNS propagation only to notice that the changes I thought I completed weren't there - I must have missed an ok/confirm button or something...

If the settings are there you could also try checking using some network other than your usual internet provider (which often is involved in the DNS propagation). Mobile/office maybe?

You can also try some online DNS lookup tools or even website verification tools - often propagation to such servers is faster than to end-user internet providers. It doesn't matter if the app is not up, all you want to see if they're able to get the IP address for your domain. If any of them can get an address then it's really just a matter of time.