Minimum length for subdomains

[GoWilkes]

Is there a problem with using a 1-3 letter for a subdomain?

I currently use https://images.example.com with a document root of /public_html/images. For the sake of brevity, about 2 weeks ago I created a second subdomain of https://i.example.com, with the same document root.

At the same time, I also created a second short subdomain of https://inc.example.com with a document root of /public_html/include.

Both show up in cPanel as created, and I don't remember any error messages. But I tried it today and discovered that i.example.com isn't working! Then I looked at the DNS in WHM, and see that there's a TXT record for the SPF for both subdomains but no A records.

I know that I can create the A records manually, but before I do, is there a reason that cPanel didn't create them?

 

[cPRex]

Hey hey! No problem with short subdomains at all, and I would also expect cPanel to create the DNS records properly on the system. It might be worth looking through the /usr/local/cpanel/logs/error_log file to see if there are any entries related to that subdomain creation around that time.

 

[GoWilkes]

The only reference I find to " i." or " inc." is on Dec 12 (hopefully none of this is sensitive, I just pasted it and changed the domain to example.com):

# Before this is a long series of "info [cpsrvd] version 11.92.0.4 online", and the
# line just before this is 15:24:32 (5 minutes prior) so I don't think it's related
==> cpsrvd 11.92.0.4 started
==> cpsrvd: loading security policy....Done
==> cpsrvd: Setting up SSL support ... Done
==> cpsrvd: transferred port bindings: 10,11,12,3,4,5,6,7,8,9
==> cpsrvd: bound to ports
[2020-12-12 15:29:30 -0500] info [cpsrvd] version 11.92.0.4 online
==> cpsrvd 11.92.0.4 started
==> cpsrvd: loading security policy....Done
==> cpsrvd: Setting up SSL support ... Done
==> cpsrvd: transferred port bindings: 10,11,12,3,4,5,6,7,8,9
==> cpsrvd: bound to ports
[2020-12-12 15:34:30 -0500] info [cpsrvd] version 11.92.0.4 online
[2020-12-12 15:36:13 -0500] info [queueprocd] Rebuilding ...
[2020-12-12 15:36:13 -0500] info [queueprocd] Dequeued the following domains
[2020-12-12 15:36:13 -0500] info [queueprocd] Dequeued i.example.com
[2020-12-12 15:36:13 -0500] info [queueprocd] rebuild_files: working on domain (i.example.com)
[2020-12-12 15:36:13 -0500] info [queueprocd] php-fpm: rebuild_files: restart fpm services for Apache
[2020-12-12 15:36:13 -0500] info [queueprocd] php-fpm: fpm services restarted
[2020-12-12 15:36:13 -0500] info [queueprocd] Rebuilding vhosts in apache conf
[2020-12-12 15:36:13 -0500] info [queueprocd] Rebuild Complete
[2020-12-12 15:36:14 -0500]: “/usr/local/cpanel/scripts/restartsrv_apache_php_fpm --graceful” called by (6210 - queueprocd - process - restartsrv)
[2020-12-12 15:36:57 -0500] info [queueprocd] Rebuilding ...
[2020-12-12 15:36:57 -0500] info [queueprocd] Dequeued the following domains
[2020-12-12 15:36:57 -0500] info [queueprocd] Dequeued inc.example.com
[2020-12-12 15:36:57 -0500] info [queueprocd] rebuild_files: working on domain (inc.example.com)
[2020-12-12 15:36:57 -0500] info [queueprocd] php-fpm: rebuild_files: restart fpm services for Apache
[2020-12-12 15:36:57 -0500] info [queueprocd] php-fpm: fpm services restarted
[2020-12-12 15:36:57 -0500] info [queueprocd] Rebuilding vhosts in apache conf
[2020-12-12 15:36:57 -0500] info [queueprocd] Rebuild Complete
[2020-12-12 15:36:58 -0500]: “/usr/local/cpanel/scripts/restartsrv_apache_php_fpm --graceful” called by (7049 - queueprocd - process - restartsrv)
[2020-12-12 15:37:28 -0500] info [queueprocd] Rebuilding ...
[2020-12-12 15:37:28 -0500] info [queueprocd] Dequeued the following domains
[2020-12-12 15:37:28 -0500] info [queueprocd] Dequeued inc.example.com
[2020-12-12 15:37:28 -0500] info [queueprocd] rebuild_files: working on domain (inc.example.com)
[2020-12-12 15:37:28 -0500] info [queueprocd] php-fpm: rebuild_files: restart fpm services for Apache
[2020-12-12 15:37:28 -0500] info [queueprocd] php-fpm: fpm services restarted
[2020-12-12 15:37:28 -0500] info [queueprocd] Rebuilding vhosts in apache conf
[2020-12-12 15:37:28 -0500] info [queueprocd] Rebuild Complete
[2020-12-12 15:37:29 -0500]: “/usr/local/cpanel/scripts/restartsrv_apache_php_fpm --graceful” called by (7890 - queueprocd - process - restartsrv)

That doesn't appear to be an error, though, just a lot of when I created them, maybe?

I created A records manually, so we'll see how that goes after they propagate.

 

[cPRex]

If you're able to reproduce the problem with another domain or subdomain it would be interesting to see those logs in real-time.

 

[GoWilkes]

Well, I just now created the "i" subdomain on another account, and it's showing up in the DNS. So... cool, I guess? No clue on why it didn't work before.

When I set them up last month, I did both "i" and "inc" on a 4-letter domain with both .CO and a .NET extensions while using cPanel v.11.92.0.4. This one was on a longer domain with a .COM extension, using v.11.92.0.6. That's the only differences that I can see.

 

[cPRex]

I don't have a good explanation for this one - all the testing I just did with one-letter subdomains worked well on my end.