DNS notes

Dig utility

Dig is a useful tool for querying DNS servers.

Usage

Basic query:

dig example.com

Query specific record type:

dig example.com A
dig example.com MX
dig example.com TXT

Query using a specific DNS server:

dig @1.1.1.1 example.com

Query with +short for concise output:

dig example.com +short

Unbound dns server

Unbound is a validating, recursive, and caching DNS resolver.

Basic configuration

For a recursive dns server you need to be able to resolve from the root servers, for that you need the root hints file.

Get root hints:

wget -S -N https://www.internic.net/domain/named.cache -O /etc/unbound/root.hints
# or with curl
curl -fsSL -o /etc/unbound/root.hints https://www.internic.net/domain/named.cache

You should have a cronjob running for this every month (as root)s

Systemd-resolved configuration

If you need to be able to bind port 53 with systemd-resolved enabled, you need to configure systemd-resolved to listen on another port besides 53, for example 5353, and then configure unbound or blocky

Edit /etc/systemd/resolved.conf

[Resolve]
DNS=9.9.9.9 8.8.8.8
DNSStubListener=no

Restart systemd-resolved

sudo systemctl restart systemd-resolved