Blocking AI traffic with DNS filtering

AI traffic is easiest to stop before it gets a clean DNS answer. Once a browser, app, or bot can resolve the domain, it starts to look ordinary from the network’s point of view. I block it at the resolver, then back that up with firewall rules and a separate lab VLAN for anything that tries to be clever.

DNS filtering blocks AI domains before they ever reach the browser

Pi-hole as the first choke point for AI domains

Pi-hole is the first place I stop it. If a client asks for a known AI domain, I want the query answered locally with nothing useful, not sent on to a public resolver where it can sail straight through. That catches a lot of casual traffic with very little fuss, which is the point of DNS filtering before the firewall starts getting involved.

Unbound recursion and local sinkhole control

I pair Pi-hole with Unbound so the local resolver stays under my control. That keeps the DNS path inside the lab and makes it easier to sinkhole domains without handing the query to Cloudflare or anyone else on the way out. If I want a domain dead, I add it to the local block list and let Unbound carry on answering everything else normally.

Wildcard blocks for model endpoints and chat front-ends

Single hostnames are never enough. AI services tend to spread across model endpoints, chat front-ends, auth paths, and content delivery names, so I block wildcard patterns where they make sense and keep the list tight enough to maintain. If a service keeps changing names, I block the whole family rather than chase each hostname one by one.

Firewall rules and VLAN isolation stop the gaps DNS cannot see

Network ACLs for devices that bypass local resolvers

DNS filtering breaks the easy path, but some devices ignore local resolvers and head straight for hard-coded DNS or raw IPs. I cover that with firewall rules and network ACLs that only allow the DNS servers I run, then block the rest at the edge of the VLAN. If a client cannot reach an external resolver, it cannot quietly sidestep the sinkhole.

Guest and work VLAN separation for unmanaged clients

I keep the lab VLAN separate from the rest of the network, and I do the same for guest or untrusted kit that has no business talking to anything sensitive. That gives me a clean place for testing AI services without mixing them into trusted traffic, and it stops a half-broken device from wandering across the network when it starts phoning home. A separate VLAN is boring in the best possible way.

Egress controls for hard-coded DNS and DoH traffic

Hard-coded DNS and DoH are where the tidy DNS plan tends to fall apart. I block outbound port 53 to anything except my resolver, then control known DoH endpoints at the firewall and the upstream egress path. If a client still wants to tunnel around that, it goes into the lab VLAN and gets treated like a problem, not a special case. Put the limit before the expensive call, or the budget will always lose.