Caching DNS Resolver

[blakegonzales]

Does DMS include a caching DNS resolver?
If not, would it be best practice to install unbound on the linux DMS host?

A lot of the services in DMS I think heavily depend on DNS requests . Some service providers rate-limit access to their pre-defined DNS resolvers, which might cause trouble.

Thoughts anyone?

[polarathene]

I am aware of it being recommended for anti-spam services, others may chime in (not something I have a strong opinion on):

• [BUG] Spamassassin no longer working due to spamhaus policy change #2918 (comment)
• https://github.com/orgs/docker-mailserver/discussions/2917
• https://docker-mailserver.github.io/docker-mailserver/v13.0/config/security/rspamd/#rbls-realtime-blacklists-dnsbls-dns-based-blacklists
• https://docker-mailserver.github.io/docker-mailserver/v13.0/config/environment/#enable_dnsbl

On a linux host, you could probably also use systemd-resolved for caching. If you're comfortable running unbound or similar instead that's fine too 👍

[blakegonzales]

Thank you for the thoroughly documented response!

I've been running unbound for a while now.. and I'll deep doing so ✅.

[casperklein]

Independently from running DMS, it's a good practice to run a local DNS cache IMO (to speed up things / reduce external DNS queries) 👍 I've been using bind9 for years, but any other software like unbound, PowerDNS, etc. is also suitable.