DNS cluster between 2 master servers?

brettcave

Member
Nov 13, 2006
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Hi,

I have a few WHM root servers, and would like to cluster them. Each of the servers hosts its own accounts / DNS.

Would I be able to configure cluster for these servers?

Would 1 server then become the master for all accounts on both servers and the other a slave for all accounts, or does each server just create slave zones on the other server?

Last question, each server has at least 2 IP's, with primary and secondary being the same server. Will setting up a cluster require all domains hosted on the server to be updated with new secondary servers?

Thanks.
Brett
 

chirpy

Well-Known Member
Verifed Vendor
Jun 15, 2002
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Go on, have a guess
You can cluster them and then all servers will be configured as master zones for all the domains hosted on all servers (cPanel doesn't bother the the master/slave concept and just makes them all masters - it doesn't matter from a DNS resolution perspective). You would then need to either move the nameserver IP assignments around the servers so they are distributed to take advantage of the clustered zones or modify each domains zone to use a nameserver record on another server. The first option is probably best, i.e.:

For example with server1 and server2 using domain.com you might have:

ns1.domain.com - points to an IP on server1
ns2.domain.com - points to an IP on server1

and

ns3.domain.com - points to an IP on server2
ns4.domain.com - points to an IP on server2

To take advantage of the cluster you would want:

ns1.domain.com - points to an IP on server1
ns2.domain.com - points to an IP on server2

and

ns3.domain.com - points to an IP on server1
ns4.domain.com - points to an IP on server2

Then change the IP assignments for the nameservers at the registrar for domain.com
 

rhenderson

Well-Known Member
Apr 21, 2005
778
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Oklahoma
cPanel Access Level
Root Administrator
I can still see it as a master/slave concept depending on your point of view and how you set the DNS on each whether it is Standalone or Synchronize Changes.

Server one is called master.server.com and server two is called slave.server.com and setup DNS clustering between the servers. On the master.server.com make the setting in the cluster box for Synchronize Changes, then on the slave.server.com and make the setting on the DNS cluster say Stand Alone. Then all the records from master.server.com will copy to slave.server.com but not vice-versa. Whereas if I set them both to Synchronize changes then DNS for both servers will update to each other, then I guess I could see this as a Master/Master concept :D
 

brettcave

Member
Nov 13, 2006
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0
151
Great, thanks for the input.

I have a few servers, and configured it as suggested. Just waiting for synchronisation to update.

rhenderson - I have set synchronise on both servers, as both servers host accounts - ie server1 has its own domains, and server2 has its own domains. Now server1 will act as a slave for server2 accounts(regardless of how the zone is configured from a technical aspect), and vice versa.

All I need to do now is update my templates. If I update zone templates as root, will it also update for my resellers and their clients?

Chirpy: I will use the following configuration, through templates:
Primary: ns1.mydomain.com (server1)
Secondary: ns3.mydomain.com (server2)

That should work with the registrars....
 

brettcave

Member
Nov 13, 2006
9
0
151
Just ran into a possible problem:

This is how I have configured my servers:

ns1.domain1 and ns2.domain1 are on server1 (S1)
ns1.domain2 and ns2.domain2 are on server2 (S2)
ns3.domain2 and ns4.domain2 are on server3 (S3)

S1 synchronises with S2
S2 synchronises with S1

S2 also synchronises with S3
S3 synchronises with S2

S1 is unable to handle the load of a reseller, so I transfer all 260 of his accounts to S3 and update all records on S1 (well, A records at least). (Hence I left out the synchronisation between S1 and S3 in my cluster).
But records go between S2, so S1 inevitable synchronises with S3 and vice versa.

Checking the responses from the nameservers, S1 still refers to itself as SOA and S3 refers to itself. Would this stay this way (i.e. if 2 synchronising servers find an existing zone, there will be no fighting over who the true master is?)

Also, S2 does not have any records for domains that were transferred... it refers me to root servers...
 
Last edited:

SoftDux

Well-Known Member
May 27, 2006
1,023
5
168
Johannesburg, South Africa
cPanel Access Level
Root Administrator
You can cluster them and then all servers will be configured as master zones for all the domains hosted on all servers (cPanel doesn't bother the the master/slave concept and just makes them all masters - it doesn't matter from a DNS resolution perspective). You would then need to either move the nameserver IP assignments around the servers so they are distributed to take advantage of the clustered zones or modify each domains zone to use a nameserver record on another server. The first option is probably best, i.e.:

For example with server1 and server2 using domain.com you might have:

ns1.domain.com - points to an IP on server1
ns2.domain.com - points to an IP on server1

and

ns3.domain.com - points to an IP on server2
ns4.domain.com - points to an IP on server2

To take advantage of the cluster you would want:

ns1.domain.com - points to an IP on server1
ns2.domain.com - points to an IP on server2

and

ns3.domain.com - points to an IP on server1
ns4.domain.com - points to an IP on server2

Then change the IP assignments for the nameservers at the registrar for domain.com

This sounds like a great idea, but I have a few questions.

I use modernbill to automatically create accounts. Now, let's say I configure modernbill to create accounts on both server1 and server2, filling them up equally, do I need to provide all 4 NS entries? And how will the cluster know which IP that domain uses?

Secondly, does the cluster only copy over the DNS records, or the accounts as well?

If, I want todo this with say 5 cPanel servers (thus having 10 NS IP's to work with, will each be a master of the other?