DNS Relay Server - Configure Local Cache
Does the DNS relay server support a local cache, and if so, how can this be configured? I would like to cache DNS queries by 1-5 minutes.
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Hi Eric Nix! The DNS Relay doesn't support local caching, and there's no setting in
relay.confto enable it.The reason for this is by design: the Relay needs to forward every lookup to DNSFilter so we can identify which device made the request, apply the correct filtering policy, and capture it in your reports. If the Relay answered from a local cache, those lookups would bypass filtering and never appear in your Query Log — so a 1–5 minute cache window would mean a 1–5 minute gap in both filtering and reporting.
It's also worth knowing that we intentionally keep DNS TTLs short so that policy changes take effect quickly — local caching on the Relay would work against that.
If you're looking to improve lookup speed, the good news is you can place a caching DNS server in front of the Relay — most networks already have one that does this by default. That gives you the speed benefit without impacting filtering or visibility.
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Wouldn't putting something in front of the relay server also defeat the purpose of what you describe (filter policy, client logging, etc.)? Plus, it would add an extra failure point. I think the relay server should have an option to customize caching for those that would like to enable it. Can be disabled by default.
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Hi Eric Nix! Good news on your first concern — the Relay already forwards local queries to a DNS server ahead of it, so placing a caching server in front wouldn't defeat the purpose or break filtering and reporting for that use case.
As for configurable caching on the Relay itself, that's not something available today, but it's a great candidate for a feature request! You can submit it at dnsfilter.canny.io/feature-requests — the more detail you include about your use case, the better.
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