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I'm attempting to get domain-b to direct to domain-a and feel like I've done it via a CNAME to a pretty standard method. Yet I'm still getting ERR_NAME_NOT_RESOLVED / server DNS address could not be found when trying www.domain-b.com.

Various DNS diagnostic sites suggest, after 24 hours, that DNS caches throughtout the world are up-to-date with my latest DNS records, which are as follows (and with the same registrar, though this shouldn't be necessary and may likely not be in the future):

Domain-B

    A       1.2.3.4 # re-direct root domain to www via registrar's own suggested method (IP just an example)    
www CNAME   domains.domain-a.com    
    MX      email.com   10
    MX      relay.email.com     20      
    TXT     v=spf1 include:email.com -all

Domain-A

    A       IP Address of server    
*   A       IP Address of server    
    MX      email.com   10
    MX      relay.email.com     20      
    TXT     v=spf1 include:email.com -all

While I need the catchall wildcard A Record for Domain-A for other reasons, I did try an explicit A Record of the domains subdomain and it didn't improve the situation.

  • domain-a.com resolves fine

  • All subdomains to domain-a.com resolve fine

  • domain-b.com redirects to www.domain-b.com com fine

  • www.domain-b.com (whether direct or via domain-b.com redirect) always returns a DNS address not found error in all browsers.

Have I overlooked something in my DNS records or should I be searching elsewhere for the culprit? I can visit domains.domain-a.com directly no problem so this leads me to believe it's not an error with any DNS records between my server host and domain-a DNS records.

biscuitstack
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    In many cases mentioning the actual domain name is essential for the community to be able to help diagnose DNS issues. This may be one too. Please refer to [this Q&A](http://meta.serverfault.com/q/963/37681) for our recommendations with regards to how and what (not) to obfuscate in your questions. - With tools like `nslookup` and/or `dig` you can query the domain servers for your domains directly and won't get your ISP's cached results, which may help with debugging DNS issues. – HBruijn Sep 21 '17 at 09:16
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    @HBruijn I can appreciate that, thanks, and am certainly limiting what can be diagnosed. In this situation I was hoping for clarification that my DNS records don't show anything unusual in themselves. I can't share the actual domain names for business reasons, unfortunately. I tried `nslookup` and `dig` yesterday with nothing unusual presenting itself but will have a look again now. – biscuitstack Sep 21 '17 at 09:18

3 Answers3

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The DNS records were fine and it turns out my ISP is just badly delayed in updating its DNS caches, despite low TTL numbers in my records. It was my lack of experience with the nslookup tool that made me miss this. I saw nothing unusual with the results, returning Got SERVFAIL reply as expected.

I didn't know you could use nslookup to run the same test from a different DNS server, and they all returned the result without a fail. I'd assumed that if other DNS global server checks were showing the records correctly in 95% of servers, my own ISP surely wouldn't be the culprit. Lesson learned. Thanks to @HBruijn for prompting me to revisit nslookup.

biscuitstack
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You'll have to lower your TTL at least TTL seconds before the change: the new TTL can't change what has already been cached, and you'd need to wait until the former TTL expires.

Also, while everything else suggests that this probably isn't the problem here, correct DNS records always have FQDNs with the tailing . i.e. literally your www.example.com. CNAME,

www    CNAME   domains.example.net

would actually be relative to the $ORIGIN i.e.

www    CNAME   domains.example.net.example.com.

rather than the correct

www    CNAME   domains.example.net.

You are probably updating your records with some tool rather than editing the actual zone file. However, when giving configuration without the actual domains, this kind of details should be corrected, first.

Esa Jokinen
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I also have the same problem with my other domain. However, the cname for domain-b should have a period because it is external. As shown below.

www CNAME   domains.domain-a.com.

This method worked for me when I pointed my domain andrewmutenga.com on Google domains to andrew.000webhostapp.com on 000webhost.

www cname andrew.000webhostapp.com.

However, I had to go to 000webhost cpanel to link the two otherwise it wouldn't have worked.

With my other domain drew.zimbo.com the above method did not work because the cpanel for zimbo.com does not have the option to link with other domains.

If you find other ways to link your domains please share with me.

Andrew Mutenga
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  • I had everything set up fine. It was my ISP being slower than many others to update DNS records (and me being silly enough to believe I'd checked this thoroughly already) that was the issue. It solved itself. See the answer above. – biscuitstack Dec 07 '17 at 17:59