Optimal DNS Cluster

DennisMidjord

• February 20, 2020 12:14

For a long time, we've been running with what I think is a very badly configured DNS cluster. We have 3 nameservers. Each name server is configured as 'Synchronize Changes' on all of our shared servers, like this: ns1.domain.com ns2.domain.com ns3.domain.com Each DNSOnly server also has name servers configured. Example for ns1.domain.com: ns2.domain.com ns3.domain.com Example for ns2.domain.com: ns1.domain.com ns3.domain.com Example for ns3.domain.com: ns1.domain.com ns2.domain.com Plus all DNSOnly instances also have each shared server configured as Standalone. Is that the optimal way to do it? It seems very impractical.

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  cPanelLauren

  • February 21, 2020 22:21

  all DNSOnly instances also have each shared server configured as Standalone. Is that the optimal way to do it? It seems very impractical.

  
  Webserver -> DNSOnly Servers in a one way sync is called a Direct link which is the optimal configuration I am having some difficulty visualizing your configuration with this explanation: You can have any number of webservers connecting to one of you DNSOnly Servers so something like this would be fine: Where Zones on the Web Servers is sent to the DNSOnly Servers but isn't sent elsewhere. There are also other types of configurations which are discussed here: Guide to DNS Cluster Configurations | cPanel & WHM Documentation

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  DennisMidjord

  • February 25, 2020 13:15

  Hi @cPanelLauren Thanks for taking your time to assist with this. This is how all of our shared web servers are configured. They're each configure with our 3 name servers. This is how each name server is configured. They're configured with all shared servers plus the remaining 2 DNSOnly servers. Is this the most optimal way to do this? It just seems to inefficient if we need to make changes. It has to be made on every single server.

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  cPanelLauren

  • February 26, 2020 19:42

  Trying to visualize this configuration and it sounds like you have X number of web servers (we'll say 50 for the purposes of example) So 50 webservers synchronize their changes to 1 nameserver which is standalone -> then 1 nameserver connects to the other two and synchronizes changes to them? If this is correct, it's not the most efficient configuration but not for the reasons you're citing. The most efficient cluster is connecting ALL of your webservers directly to the nameservers as I showed in the diagram. In your situation, you have a Primary DNS Server and an Intermediary, the issue with that configuration being that you place another step in the synchronization process. There's no real centralized server management tool yet which is what it sounds like you're *really* looking for. 1 place to make changes for all your webservers.

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  DennisMidjord

  • February 26, 2020 19:57

  So 50 webservers synchronize their changes to 1 nameserver which is standalone

  
  No, all web servers are actually connected to all (3) name servers. The first image in my previous post is how all web servers are setup (you see the three name servers). The second image is how all three name servers are setup: Connected to all web servers as standalone, and connected to the remaining two name servers as sync only. Is that the most efficient way?

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  cPanelLauren

  • February 26, 2020 20:15

  Either way, you look at this you have an issue where the nameservers are connected to each other and they shouldn't be if you want the most effective resolution.

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  DennisMidjord

  • February 27, 2020 07:35

  So instead of having each nameserver connected to all web servers AND the remaining nameservers, I should just have each nameserver connected to the web servers and nothing else? :)

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  cPanelLauren

  • February 27, 2020 17:00

  To clarify what I mean, using this graphic as an example (imagine the total number of web servers = your total number)

  • 1-way sync from webserver to the nameserver
  • All web servers connected directly to nameservers
  • no nameservers synchronize with anything

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  DennisMidjord

  • February 28, 2020 08:42

  Thanks, @cPanelLauren. If I understand your graphic, our current setup is this (notice the arrows between the nameservers), right? I forgot to add an arrow from NS1 to NS3 and the other way around, but I hope it makes sense. We would just have to remove each nameserver from eachother? One thing that worries me about this: What happens if a nameserver goes offline? Does it automatically sync DNS zones when coming online again?

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  cPanelLauren

  • February 28, 2020 16:33

  Thanks for the graphic it really helps understand the configuration quickly. Synchronizing the records from the NS to each other is probably not doing you much good, each of them gets their DNS records from the webservers and you are leaving yourself open to duplicate records if the synchronization timing is delayed in any respect. I would stop just that portion, otherwise, the configuration is good. If one nameserver goes offline, the other will take over for it so to speak. In the event this does happen as soon as it's back online changes on the webserver will be synchronized to the DNSOnly server that doesn't have updated records.

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  DennisMidjord

  • March 02, 2020 10:21

  Thanks!

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