[Feature]: Unable to configure both search domain and ~. routing domain in DNS settings

[frq-asgard-migo]

Problem description

Currently, Defguard only allows setting a single domain value in the DNS configuration. If a domain is specified (e.g. domain.local), it is applied as a search domain. If left empty, it defaults to ~. (global routing domain).

Not possible:
DNS: 192.168.1.2,192.168.100.5,domain.local ~.

This creates a limitation when using Linux systems with systemd-resolved, where it is often necessary to define both:

• a search domain (e.g. domain.local) for short hostname resolution
• and a routing domain (~.) to ensure all DNS queries are sent through the intended resolver (e.g. VPN DNS)

Problem:

There is currently no way to configure:

domain.local ~.

This leads to issues such as:

• Short hostnames (e.g. testvm01) not being resolved automatically
• Inconsistent DNS behavior compared to other platforms (e.g. setups where search domains work as expected)

Expected behavior:

Allow configuring multiple domain entries so that both search and routing domains can be applied simultaneously.

Proposed solution

Allow multiple domain values (space-separated), e.g.:

• domain.local ~.

Or provide separate fields for:

• Search domains
• Routing domains

Alternatives considered

Dropping the search domain (domain.local) entirely and relying only on the default ~. routing domain.
This would avoid the configuration limitation, but would also mean losing short hostname resolution (e.g. testvm01 would no longer resolve to testvm01.domain.local).

Impact

Important