SubDomain Not Stable.

[jeffery]

I have created hundards of account user this format :

subdomain.mydomain.com

However, sometimes serveral subdomain give a DNS error, and now, all subdomain except www.mydomain.com is working..


Can anyone please suggest why is it so?

:confused:

[DirectAdmin Support]

DNS propogation can sometimes take several hours. The "dig" command is the best way to debug subdomain dns issues:

dig sub.domain.com @1.2.3.4

where 1.2.3.4 is the IP of the nameserver you are running them on. If you're on the same machine, then you can just use 127.0.0.1

If you want all subdomains to resolve instantly, it's easiest to add a wildcard to your dns settings

* -> 1.2.3.4

John

[jeffery]

I am not sure why the sub-domain will suddenly become unavailable, I haven't change the nameserver of the domain.



If you want all subdomains to resolve instantly, it's easiest to add a wildcard to your dns settings

John, can you explan more about this? :D

[DirectAdmin Support]

A wildcard dns record means that any subdomain accessed at that domain that isn't specified in the zone will resolve to the IP specified at that IP.

We have a simple example zone:

www A 1.2.3.4
ftp A 1.2.3.4
mail A 1.2.3.4
* A 1.2.3.4Alright.. when someone accesses www.domain.com, www resolves to 1.2.3.4 because it's in the zone.. quite simple. If someone accesses bob.domain.com, it's not in the zone, but because the wildcard dns is there, it will catch all unknown hosts and send them to 1.2.3.4 as well.

This allows older dns records on your ISPs nameserver to work for brand new subdomains because they know that anything.domain.com should resolve to 1.2.3.4 if it isn't in the zone. When you add the subdomain to the zone, the A record will be added and given time, it will take priority over the *, but becaue they can work together, you won't notice any problems.. and everything should be working after apache restarts (so 1 minute after you add the subdomain)

:)

John

[jeffery]

Thanks John! :)