On 07/22/2014 08:00 AM, Mark Heslin wrote:
Martin, Petr,

I didn't see that missing dot "." - good catch. As always the devil is in the details :-)

Two follow up questions:

1. I've set the priority and weighting equally here but I will add a third host so would it make sense to just set both priority and weight to "0" for all three hosts?:

# ipa dnsrecord-add example.com _foo.tcp --srv-rec="0 0 53 foo1.example.com." # ipa dnsrecord-add example.com _foo.tcp --srv-rec="0 0 53 foo2.example.com." # ipa dnsrecord-add example.com _foo.tcp --srv-rec="0 0 53 foo3.example.com."

2. To Petr's point about registering the "_foo.tcp" service. By definition this isn't really a true "service" and more like "CNAME with benefits". (Sorry, couldn't resist the bad dating reference ;-)) Do I actually still need to add this to /etc/services? If so, then I'd have to do that for
      all hosts in the environment, IdM servers, clients, etc., correct?

Truth be told, this is just being used for an alternative to a true h/w, s/w load balancer for demonstration purposes so I'm sure adding it to the services file makes sense.

Gah! I meant to say I'm *not* sure adding it to the services file makes sense.

Thank you both!


On 07/22/2014 03:16 AM, Petr Spacek wrote:
On 22.7.2014 00:13, Mark Heslin wrote:
Hi All,

I had some off-list exchanges with Petr Spacek on this but am still trying to
work out the correct syntax.
I have 2 hosts:

    - foo1.example.com
    - foo2.example.com

and would like to create a round-robin DNS srv record for both called

I already have DNS entries for both hosts in IPA:

   # ipa dnsrecord-show example.com foo1
     Record name: foo1
     A record:
   # ipa dnsrecord-show example.com foo2
     Record name: foo2
     A record:

I'd like to get the correct syntax for adding the srv record for foo.
My understanding is that it should be something like this:

# ipa dnsrecord-add example.com _foo.tcp --srv-rec="0 50 53 foo1.example.com"
   Record name: _foo.tcp
   SRV record: 0 50 53 foo1.example.com
# ipa dnsrecord-add example.com _foo.tcp --srv-rec="0 50 53 foo2.example.com"
   Record name: _foo.tcp
   SRV record: 0 50 53 foo2.example.com

which seemed to be added ok but on second glance I think not:

   # host -t srv _foo.tcp.example.com
_foo.tcp..example.com has SRV record 0 50 53 foo1.example.com.example.com. _foo.tcp..example.com has SRV record 0 50 53 foo2.example.com.example.com.

In looking over the description of rfc2782
<http://en.wikipedia.org/wiki/SRV_record> it appears the IPA syntax is a
little different,

I don't think so :-)

Please note the trailing dot in "target" part of http://en.wikipedia.org/wiki/SRV_record#Record_format.

IPA behaves in the same way as BIND 9: All domain names without trailing dot are automatically extended with zone origin, i.e. "example.com.".

You have two options:
# ipa dnsrecord-add example.com _foo.tcp --srv-rec="0 50 53 foo1" (DNS server will automatically append "example.com.")


# ipa dnsrecord-add example.com _foo.tcp --srv-rec="0 50 53 foo1.example.com."
(please note the trailing dot)

Another note is about "_foo". "foo" should be "service name" according to http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml

It will probably not cause any problems if you invent your own name (preferably prefixed with x- to avoid collisions in future, e.g. "_x-foo"), but it will not hurt you if you register your protocol into the registry :-)
See http://tools.ietf.org/html/rfc6335

and the documentation is scarce so admittedly I'm taking a swag at this ;-)

I can do this fine without srv but don't have enough familiarity with DNS srv
Can anyone help clarify what I'm missing? I'd like to have equal weighting,
to both hosts - I'm assuming the port (53) is correct for DNS here as well.
What are you trying to achieve? The port number refers to port used by your application, not to DNS.


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