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DNS Host Definitions not updating

Hello Community,

we do have 2 Domain Controllers with Sophos UTM Cluster.

The Domain Controllers handle DNS Services and are used by the UTM to work with DNS Hosts.

We do work with DNS Host Definitions and i recently moved a Host from one VLAN to another, therefore the IP address has changed.

After a reboot of the corresponding machine the DNS Record has been successfully updated on the Domain Controllers and i verified that the new entry has its 15Min TTL Property.

I waited the whole night but the Firewall was still resolving the Host with its old IP, i had to manually clear the resolver cache for the UTM to Update the Record.

Shouldn´t this be some sort of automatic process, am i missing something ?
Thanks



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  • Is your UTM set up so that it's just a forwarder, so any requests passthrough to the DNS server?

    OPNSense 64-bit | Intel Xeon 4-core v3 1225 3.20Ghz
    16GB Memory | 500GB SSD HDD | ATT Fiber 1GB
    (Former Sophos UTM Veteran, Former XG Rookie)

  • Hello Amodin,

    The client get the DCs as their primary and secondary DNS, the domain Controllers point to the UTM as their Resolver and the UTM is using DNS Servers provided by our local ISP. There is a request route in place for domain.local pointing to our domain controllers.
    Everything seems to work fine but the DNS Host entries on the utm stay as they are despite being changed manually or due to automatic dns updates on Domain Server level. I have to flush the cache for the entries to get renewed

Reply
  • Hello Amodin,

    The client get the DCs as their primary and secondary DNS, the domain Controllers point to the UTM as their Resolver and the UTM is using DNS Servers provided by our local ISP. There is a request route in place for domain.local pointing to our domain controllers.
    Everything seems to work fine but the DNS Host entries on the utm stay as they are despite being changed manually or due to automatic dns updates on Domain Server level. I have to flush the cache for the entries to get renewed

Children
  • Hmm sounds like the old DNS bug around ... I wanna say version 7.9 - 8.0?  I can't say for certain on that, but I think the difference here is that you can resolve once you flush the cache, whereas the older bug wouldn't update after a flush.

    Is your internal DNS Hosts on the UTM set up with reverse DNS and using the in-addr.irpa addressing? Is there anything in your logs, or have you tried to access the 'lost' clients via IP?

    OPNSense 64-bit | Intel Xeon 4-core v3 1225 3.20Ghz
    16GB Memory | 500GB SSD HDD | ATT Fiber 1GB
    (Former Sophos UTM Veteran, Former XG Rookie)

  • Hello Amodin, the reverse DNS Lookup has not been setup, i can connect the lost clients via IP without any issues.
    i found out that some entries are static and some are dynamic, and that there is no vanishing enabled i think i will dig deeper and setup some test hosts to play around with, Thanks!