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I'm trying to consolidate domain names for the servers I look after to just use one panel instead of 3 or 4, and one thing stopping me is that the provider I originally wanted to move them to only lets me the following kinds of records:

  • A
  • MX
  • NS
  • CNAME
  • TXT

The first four I understand, but I'm not sure about the relationship (if any) between SRV records and TXT records.

Can I use TXT records in the place of SRV records? They both seem to be general text records to just point at a particular server without needing to specify a particular protocol, so it doesn't sound like a totally unreasonable assumption, but I'd rather check here before I break something.

If I can only set the above records, does that mean I'm essentially unable to so any SRC record redirecting?

Thanks!

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No SRV and no AAAA? It seems a sufficient reason to drop that provider and to switch to a serious one. What's its name? –  bortzmeyer Jun 4 '10 at 7:22
    
It is surprising (to me, anyway) how many providers still don't support srv records. I still encounter some that don't support txt records either. Frustrating. As bortzmeyer said, when that happens you might have to start shopping for a new provider. That having been said, I have encountered some providers that don't support txt and srv via their website but they do allow you to call in to request them. That isn't at all optimal of course but in some scenarios might be helpful. –  icky3000 Apr 13 '11 at 21:45
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3 Answers

up vote 15 down vote accepted

TXT records are free-form text records and can be used for things like describing hosts. Can also be used for application specific goals, like DNSBL and SPF. Nowadays, they're widely used to accomplish both these goals.

SRV records are service records and are a kind of extension of MX records and are a little more complex than TXT records. While MX records are used to define which servers will handle the e-mail for a specific domain, giving different weights to different records, SRV records are used to provide things such as the protocol and the port. A SRV record has the following form:

_Service._Proto.Name TTL Class SRV Priority Weight Port Target

Service: the symbolic name of the desired service.

Proto: the transport protocol of the desired service; this is usually either TCP or UDP.

Name: the domain name for which this record is valid.

TTL: standard DNS time to live field.

Class: standard DNS class field (this is always IN).

Priority: the priority of the target host, lower value means more preferred.

Weight: A relative weight for records with the same priority.

Port: the TCP or UDP port on which the service is to be found.

Target: the canonical hostname of the machine providing the service.

One typical example of usage of SRV records is when using the XMPP protocol. For instance, if you have a foobar.com domain, the A record would be used to define the servers where your web contents are and the SRV records would be used to define where your XMPP server is. Typically, they will be located in different addresses.

More info about SRV records here.

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SRV records are no more related to TXT records than A or CNAME records are.

Are you thinking of SPF records (which are broadly identical to SPF entries carried within TXT records)?

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SRV records are for creating fine-granularity descriptions of services. These are heavily used in some environments, such as Microsoft Active Directory. They are typically specific to a protocol or service, and provide priorities and weights to create preferences in selection (poor-mans load balancing).

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