bind replication between sites

[Dave Henderson]

Thanks for the reply Chris.  I am confused as to why changing the  refresh cycle wouldn't be the simple fix the to problem.  Isn't  that how long a slave is supposed to wait before it contacts the master  to see if updates are available?  If so, then that is why mine  wasn't working (it was set for 7 days).
  
  I have two slave servers.  One is on the same network segment as  the master and the other is at a remote site.  The firewalls are  configured to forward DNS traffic to the correct servers and everything  seems to be working now that the values are much lower.
  
  My SOA does show the master BIND server name (which is resolvable on both slaves).
  
  Thanks again for your help and any other advice you have.
  
  Dave
  
Chris Buxton <cbuxton at menandmice.com> wrote:  The refresh, retry, and expire timers shouldn't matter as long as  
notify is working.

BTW: Don't set expire as low as refresh, or you risk having your  
slave take itself offline for no reason. In most cases, expire should  
be at least a week, regardless of refresh and retry.

Your problem is that DNS Notify is not working. This can be hidden by  
setting refresh and retry to very low values, but it's better to  
figure out why notify is not working.

Are your servers behind a NAT firewall, on private addresses? That  
will often cause notify to fail, since the master will notify the  
slave's public address, but the NAT server can't handle internal-to- 
internal communication through NAT'd addresses. This can be worked  
around by setting also-notify in your zone statements, listing the  
slave server.

Are your zone's NS records correct? Does your SOA show your master  
server as the mname, or the slave? The master will not notify the  
server listed by the SOA as the zone's master.

Chris Buxton
Men & Mice

On Jul 22, 2006, at 4:25 PM, Dave Henderson wrote:

> Sten,
>
>       After looking at the SOA portion, I noticed its  numbers  
> where way to high for what I was trying to accomplish.  I  have  
> since adjusted them and everything seems to be working fine.    
> Thanks to everyone who helped.
>
>   Dave
>
>
> Sten Carlsen  wrote:  Ok, a few more  
> questions:
> After making the change with your script, do you check the new SOA  
> with
> dig? (dig  axfr) does it show the new incremented serial?
> And back to Kevins question what are the times involved in the SOA,
> specially the refresh time. You could try to make that short, like 5
> minutes for the experiment and see if that gets the zone updated  
> when it
> expires.
>
> A couple of other things to consider: is axfr allowed from both  
> slaves?
> is any firewall open for both UDP and TCP transfers with the proper  
> port
> numbers?
>
> If this does not ring a bell, I think you should publish the relevant
> named.conf and zone files from both master and slaves here. Please do
> not change anything, except keys for TSIG, rndc and like. Any editing
> can inadvertently make changes that hide the real problems from  
> view and
> draw attention into the wrong direction delaying the solution. I am
> pretty sure that a lot of people on the list will look at the real  
> files
> and analyse them.
>
> Dave Henderson wrote:
>> Sten,
>>
>>  You are correct in your first paragraph. I can create a brand new  
>> zone  and it gets propagated to both slave servers. Any changes  
>> made to that  new zone do not get replicated. And I have been  
>> increasing the serial  number. I wrote a perl script that adds/del/ 
>> updates the record and  increases the serial number. I verified  
>> all content  added/deleted/updated via the script is correct, but  
>> still no slave  servers get updated.
>>
>> The reason the serial numbers  are low is because they are the  
>> ones listed on the slave server. The  ones on the master are up to  
>> 17. There shouldn't be a problem at all.
>>
>>   DHCP can be ruled out because these aren't clients creating  
>> dynamic DNS entries (so no its not a stupid wintel client).
>>
>>   Dave
>>
>>
>> Sten Carlsen  wrote:  As I read the original post:
>> from starting the slave server with no zone file on it, the  
>> replication
>> takes place as it should and after a short there is a zone file on  
>> the
>> slave server. So far all ok.
>> Next, if a change is done on the master that change is not  
>> propagated to
>> the slave server.
>>
>> Is this the correct description of the problem?
>>
>> If this is so, I would like to ask if you remember to increase the
>> serial number in the master zone file? or use nsupdate or dhcp to  
>> update
>> the zone?
>>
>> I noticed the serial numbers from the log files being very low,  
>> possibly
>> indicating that they were not incremented. This would present the  
>> exact
>> picture I explain at the top of this post.
>>
>> Kevin Darcy wrote:
>>
>>> Dave Henderson wrote:
>>>
>>>
>>>> Gang,
>>>>
>>>>  I have three bind servers running. Two at site 1 (one master  
>>>> and one  slave) and the other at site 2. Replication of the zone  
>>>> file seems to  take place, but when updates are made on the  
>>>> master server, they don't  get replicated to the slaves.
>>>>
>>>>
>>> I don't quite understand that sentence. The file is replicating  
>>> but the
>>> changes aren't (???)
>>>
>>>
>>>> Here is a  snippet from the log of the master if I delete the  
>>>> file on a slave  server:
>>>>
>>>>   Jul 19 13:55:55 localhost named[8329]: client  
>>>> 192.168.0.31#32936: transfer of 'esessen.org/IN': AXFR started
>>>>
>>>>   and here it is on the slave server:
>>>>
>>>>   Jul 19 13:55:53 localhost named[7857]: zone esessen.org/IN:  
>>>> transferred serial 3
>>>>   Jul 19 13:55:53 localhost named[7857]: transfer of  
>>>> 'esessen.org/IN' from 192.168.0.11#53: end of transfer
>>>>   Jul 19 13:55:53 localhost named[7857]: zone esessen.org/IN:  
>>>> sending notifies (serial 3)
>>>>
>>>>
>>>>  That all seems to work ok, but if I make change to a domain, it  
>>>> doesn't  get replicated. There are no records on the master  
>>>> server indicating a  transfer at all. The slave contains:
>>>>
>>>>   Jul 19 13:55:52 localhost named[7857]: zone cliquesoftware.com/ 
>>>> IN: sending notifies (serial 2)
>>>>
>>>>   The actual serial number on the master is 17.  Here is the  
>>>> master log (after a restart):
>>>>
>>>>   Jul 19 11:19:41 localhost named[8329]: zone cliquesoftware.com/ 
>>>> IN: loaded serial 17
>>>>   Jul 19 11:19:41 localhost named[8329]: zone cliquesoftware.com/ 
>>>> IN: sending notifies (serial 17)
>>>>
>>>>
>>>>
>>> How long have you waited and what is the REFRESH setting on the  
>>> zone? If
>>> there's something wrong with the NOTIFY mechanism for this zone,  
>>> then it
>>> could take up to REFRESH time for the changes to replicate.
>>>
>>> If NOTIFY is broken, then that could be tackled as a separate issue.
>>> Better to establish that normal REFRESH-timed replication works  
>>> before
>>> getting into the arcana of NOTIFY.
>>>
>>>
>>>>   I am getting the following on the master, but I don't have a  
>>>> server or client using the following ip address:
>>>>
>>>>  Jul 19 12:11:20 localhost named[8329]: client  
>>>> 192.168.0.200#2679:  updating zone 'digital-pipe.local/IN':  
>>>> update failed: 'RRset exists  (value dependent)' prerequisite  
>>>> not satisfied (NXRRSET)
>>>>   Jul 19 12:11:20 localhost named[8329]: client  
>>>> 192.168.0.200#2682: update 'digital-pipe.local/IN' denied
>>>>
>>>>
>>>>
>>>>
>>> Probably just a stupid Wintel client that's misconfigured to  
>>> register
>>> its name in DNS.
>>>
>>>
>>>                                        - Kevin
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>
> -- 
> Best regards
>
> Sten Carlsen
>
> Let HIM who has an empty INBOX send the first mail.
>
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