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SRV Record: _xmpp-server._tcp.meet.domain.com => target=server-name.domain.com (A Record)

CNAME: meet.domain.com => target=server-name.domain.com (A record)

As you can see, the word "meet" already a "sub-domain" under domain.com (for the SRV records in meet.domain.com). Can the same word "meet" also be a CNAME under the zone "domain.com" ?

Is this allowed?

HashSRVDNS
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1 Answers1

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As you can see, the word "meet" already a "sub-domain" under domain.com (for the SRV records in meet.domain.com).

Yes, but note that it is not necessarily defined as its own zone with its own NS and SOA records.

Can the same word "meet" also be a CNAME under the zone "domain.com" ?

This should work as long as you don't want to create any other records for the name meet.domain.com (since if a name has a CNAME record it can't have any other records associated with it).

Grisha Levit
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  • Yes, but note that it is not necessarily defined as its own zone with its own NS and SOA records ::

    This is not the case for us here. A new DNS zone is going to be created for meet.domain.com

     – HashSRVDNS Jan 15 '17 at 07:58
  • This should work as long as you don't want to create any other records for the name meet.domain.com (since if a name has a CNAME record it can't have any other records associated with it) ::

    "should" ? This is in production and I am looking to hear from someone who has tried something similar and confirm it is working.

     – HashSRVDNS Jan 15 '17 at 07:59
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    A new DNS zone is going to be created for meet.domain.com Well, you can't have the apex of your zone be a CNAME. There are lots of posts here that explain this better than I can. But my main point was the fact that the existence of SRV a.b.c.com does not preclude the existence of CNAME b.c.com. – Grisha Levit Jan 15 '17 at 08:01
  • Thanks for replying. But why can't the apex of zone be not a CNAME? In my case the CNAME "meet" is hosted under example.com and the subdomain of "meet" is going to have its own SOA etc. I don't quite understand why would this be a problem. – HashSRVDNS Jan 15 '17 at 09:43
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    Apex CNAMEs are illegal per RFC 2181. If you create a new zone, that zone will have mandatory NS and SOA records at the apex. A CNAME record cannot coexist with the majority of record types. – Andrew B Jan 15 '17 at 09:50
  • @AndrewB : But the CNAME for "meet" will exist in "example.com" zone and the meet.example.com will have its own SOA. Am I completely wrong with this understanding? If not, why should CNAME record in top domain affect the sub-domain? – HashSRVDNS Jan 15 '17 at 13:25
  • If meet is a CNAME in example.com then it can't also be a subdomain of example.com. When a resolver queries example.com name servers for meet.example.com it can receive either a referral for the meet.example.com servers or a response that meet is a CNAME. – Grisha Levit Jan 15 '17 at 17:57
  • Thanks @GrishaLevit : Will the problem go away if "meet" was a A Record instead of CNAME? – HashSRVDNS Jan 16 '17 at 01:36
  • Yep, an A record is fine. – Grisha Levit Jan 16 '17 at 02:19