Odi's astoundingly incomplete notes

New entries | Code

Be bloody careful with CNAME records

Be careful when doing something stupid!

CNAME records are useful. Especially together with external hosting services.
You run your domain and control DNS yourself but you host a website on an external service. They manage the IP of that site and give you a name that may look like examplesite383.hostingprovider.biz and already points to the correct IP. You want to map it into your DNS zone with a nice name like www.fancyproduct.com so creating a CNAME that points tha name www to your hosting provider's name is a practical way to go. You also want to do the same without the www prefix, but mind you! Creating a CNAME for fancyproduct.com would redirect the complete zone to a different one!

Never create a CNAME record for the zone name!

Also when caches start picking up the SOA information of the wrong zone, they apply the TTL values of that zone. So getting control of your zone back may not be easy and is not under your control anymore.

Also any secondary DNS server will pickup the zone redirect and may completely stop updating the zone from your authorative server. You need to manually fix that on the secondary DNS!

posted on 2018-10-02 10:01 UTC in Code | 0 comments | permalink