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I have 2 domains: domainA.com and domainB.com. I have 1 website (say served by IP xxx.xxx.xxx.xxx:80)

domainA.com is the preferable name, but I want domainB.com to be usable as well.

I am not concerned about SEO at this point (but might be in the future).

What is the proper way to setup DNS, such that:

  • DNS handles requests for domainA.com directly and refers to the website at xxx.xxx.xxx.xxx:80
  • domainB.com forwards all requests to domainA.com

Can I simply create an A record in each zone that points to xxx.xxx.xxx.xxx? Or, is there any way to point domainB.com at domainA.com using only DNS?

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I am really digging the additional comments bringing to light the nuances of when each technique is best used. Thanks SOers. –  jmsmcfrlnd Sep 10 '10 at 14:50

3 Answers 3

up vote 2 down vote accepted

While it's certainly possible to create a CNAME for domainB.com to point to domainA.com, it's usually not recommended unless you can fully grasp the ramifications of doing so.

I'd just recommend creating two DNS A records, one for each domains, pointing to the same IP address. Then in your apache config, do something like this:

<VirtualHost *:80>
    ServerName domainA.com
    ServerAlias domainB.com

    DocumentRoot /path/to/root
    ...
</VirtualHost>

Can I simply create an A record in each zone that points to xxx.xxx.xxx.xxx:80?

No, DNS records have nothing to do with TCP/UDP ports. Your application (a web browser in this case) will need to take care of that.

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thanks for clarification, it's just late and I'm tired. I will edit out the :80 in reference to A record. –  jmsmcfrlnd Sep 9 '10 at 3:01
    
Can you briefly state the ramifications of using CNAME of domainB pointing to domainA? –  jmsmcfrlnd Sep 9 '10 at 3:04
    
@arrochar - Basically the CNAME follows the A record that it points at, so if you want to change where DomainA is and leave domainB, it requires reconfiguration of DNS entries which are cached across the Internet. –  MDMarra Sep 9 '10 at 3:34
1  
In addition to what MarkM stated, all records for domainB.com will follow the CNAME, including any MX, PTR, etc. records. –  EEAA Sep 9 '10 at 3:46
    
True and this can be good or bad. For example, if you have domainB only for backward compatibility needs or to address mispelling errors, the all records follow to domainA is what you need but if you have only a commom application on both domains and the rest is different, then CNAME is not the good way. –  laurent Sep 9 '10 at 16:27

You can use an A record on each domain pointing to the same IP without problems but I prefer to create a CNAME record in domainb.hosts pointing to domainA.com server name (not IP). A nslookup to domainB.com will return you the IP and the cannonical name domainA.com server name.

Web server have to handle both name. If Apache, you can use ServerName www.domainA.com and ServerAlias www.domainB.com

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I'm not an dns expert, but I think you can create an cname to domainB appoint to domainA and config your http server, to respond to domainA and B in same website.

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