Modify the file /etc/systemd/resolved.conf

add “Domains=xxxx.xxxxx” to the file

xli@xxxxxxx-vm:~$ more /etc/systemd/resolved.conf

This file is part of systemd.

#

systemd is free software; you can redistribute it and/or modify it

under the terms of the GNU Lesser General Public License as published by

the Free Software Foundation; either version 2.1 of the License, or

(at your option) any later version.

#

Entries in this file show the compile time defaults.

You can change settings by editing this file.

Defaults can be restored by simply deleting this file.

#

See resolved.conf(5) for details

[Resolve]

DNS=

FallbackDNS=

Domains=

LLMNR=no

MulticastDNS=no

DNSSEC=no

DNSOverTLS=no

Cache=yes

DNSStubListener=yes

ReadEtcHosts=yes

Domains=internal.xxxxxx.xxxxx
xli@xxxxxx-vm:~$
xli@xxxxx-vm:~$
xli@xxxxxx-vm:~$ nslookup rds
Server: 127.0.0.53
Address: 127.0.0.53#53

Non-authoritative answer:
Name: rds.xxxxx.xxxx.xxxxxx
Address: 10.137.1.x