[Freeipa-users] Correct *usage* for round-robin DNS srv records

[Petr Spacek]

On 23.7.2014 18:01, Mark Heslin wrote:
> Hi Alexander,
>
>  >SRV records need to be resolved first by your software and then resolved
>  >records used to perform lookups of the SRV entry content.
>
> Ah, yes that explain it.
>
>  >If your clients don't know how to do that, you  can use multiple A/AAAA
>  >record entries to allow round-robin them.
>
> The funny thing here is that this is how I initially configured this (A Recs)
> but it was suggested
> that I use srv records. Since the OpenShift client do not make use of srv
> records then I'll go back
> to my initial configuration with A records.
>
> At least now I understand srv records better and this will be used more and
> more in the future:-)

Oh, I didn't expect that your application is so dumb. Please open bugs 
upstream to fix that.

Have a nice day!

Petr^2 Spacek

> On 07/23/2014 10:11 AM, Alexander Bokovoy wrote:
>> On Wed, 23 Jul 2014, Mark Heslin wrote:
>>> Martin, Petr,
>>>
>>> Thanks for helping me sort through the syntax. I have the entries added
>>> properly:
>>>
>>>  # ipa dnsrecord-show example.com _foo.tcp
>>>    Record name: _foo.tcp
>>>    SRV record: 0 0 53 foo1.example.com., 0 0 53 foo2.example.com.
>>>
>>>  # host -t srv _foo.tcp
>>>  _foo.tcp.example.com has SRV record 0 0 53 foo2.example.com.
>>>  _foo.tcp.example.com has SRV record 0 0 53 foo1.example.com.
>>>
>>> but how to I actually use the entry?
>> You are already using it above with host command.
>>
>>>
>>> # nslookup _foo.tcp
>>> Server:        10.19.140.101
>>> Address:    10.19.140.101#53
>>>
>>> *** Can't find _foo.tcp: No answer
>>>
>>> # nslookup _foo.tcp.example.com.
>>> Server:        10.19.140.101
>>> Address:    10.19.140.101#53
>>>
>>> *** Can't find _foo.tcp.example.com.: No answer
>> This is SRV record, so you need to tell nslookup to look up SRV record,
>> not A or CNAME as it does by default.
>>
>>>
>>> # ping _foo.tcp
>>> ping: unknown host _foo.tcp
>> SRV records need to be resolved first by your software and then resolved
>> records used to perform lookups of the SRV entry content.
>> http://en.wikipedia.org/wiki/SRV_record
>>
>>>
>>> The point of this is to create a front-end to balance requests from
>>> OpenShift clients
>>> across a set of OpenShift brokers. Host "foo" would alternate across the
>>> first broker
>>> (foo1) and second broker (foo2).
>> Then OpenShift clients (software) need to know how to resolve SRV record
>> prior to
>> connecting to the host that is pointed by the record.
>>
>> If your clients don't know how to do that, you  can use multiple A/AAAA
>> record entries to allow round-robin them.


-- 
Petr^2 Spacek