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We updated CNAME on a production website, after updating it website showed "server's DNS address could not be found" message for about 8 mins. Could this be because of the change in CNAME?

Dhawal
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  • There isn't much in the way of information here, so all we can say is "maybe". You'd need to tell us the steps followed, the exact order they were taken in, and confirm whether or not the record the CNAME is pointing at has also changed recently. (if so, if it has a longer TTL than the record replaced by the CNAME, bad things can happen) – Andrew B Apr 19 '16 at 20:51
  • @andrew - We are using Akamai as our CDN. Original CNAME was the one provided by Akamai, we were trying to debug an issue by bypassing Akamai, so we updated CNAME to Origin server IP and that's when this issue occurred. – Dhawal Apr 20 '16 at 00:58
  • Did you change the value of the `CNAME` record to an IP address, or did you change it to point at an `A` record which already had the IP? Your wording implies the first, and that definitely would have broken the website. `203.0.113.0` as a CNAME value translates to `203.0.113.0.example.com.`. (where "example.com" is the name of your domain) – Andrew B Apr 20 '16 at 03:50
  • @AndrewB - You are right, can you please post this as an answer so that I can accept it. Thanks – Dhawal Apr 20 '16 at 06:06

3 Answers3

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Did you change it as a delete/create or as a update? Delete/create could cause an outage. A straight update is safe and does not result in a not-found message.

Jason Martin
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From our discussion in the comments, it looks like you attempted to set an IP address target using a CNAME record. This record type is only intended to alias the host resources of one name to another, and the value will be interpreted as a name even if you input an IP address.

Input:

 $ORIGIN example.com.
 www     IN CNAME 203.0.113.0

Effective output with FQDNs:

 $ORIGIN example.com.
 www.example.com.     IN CNAME 203.0.113.0.example.com.

This mistake almost always results in NXDOMAIN (barring wildcard matching), as the target is very unlikely to exist.

Andrew B
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If you have added the CNAME records for your domain with the record name www or with a blank record name, your website may not be accessible until the DNS records are propagated.

mohemmadAli
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  • Blank record name implies apex CNAME, which [is illegal anyway](http://serverfault.com/questions/613829/why-cant-a-cname-record-be-used-at-the-apex-aka-root-of-a-domain). – Andrew B Apr 19 '16 at 20:49