[plug] Strange DNS issue

[Alex H.]

We are dealing with a rather strange DNS issue and I am hoping somebody will be able to assist us with understanding.

 

Via DHCP we are allocated two DNS servers

 

resolvectl 
Global
         Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
  resolv.conf mode: stub

Link 2 (eth0)
    Current Scopes: DNS
         Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 10.1.1.1
       DNS Servers: 10.1.1.1 10.1.1.2
        DNS Domain: reddog.domain.local

Link 3 (enP28932s1)
    Current Scopes: none
         Protocols: -DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported

The reverse lookup completes successfully

 

dig -x 10.1.1.1 and dig -x 10.1.1.2 both correctly resolve to the DNS server's hostnames

 

However the forward lookup fails 

 

dig dnsserver1.domain.local -> Fails

dig dnsserver2.domain.local -> Fails 

 

However with specifying the DNS server explicitly the requests complete successfully

 

dig @10.1.1.1 dnsserver1.domain.local -> Works

dig @10.1.1.1 dnsserver2.domain.local -> Works 

dig @10.1.1.2 dnsserver1.domain.local -> Works

dig @10.1.1.2 dnsserver2.domain.local -> Works

 

I don't understand why it works when we set the DNS server and fails when using the default system DNS servers.

 

Kind regards

Alex

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.plug.org.au/pipermail/plug/attachments/20251208/75bfcf41/attachment.htm>