The DNS Resolution Agent: Why It's a Good First Project

Bounded scope. Read-only signals. Clear success criteria. Why the DNS investigation agent is the project to ship before harder ones, plus the skeleton.

Why this scope is good

Bounded inputs: a hostname, a query type, an environment. Three inputs; nothing else.

Read-only signals: dig, nslookup, DNS cache contents. Nothing the agent does changes the world.

Clear success criterion: did the resolution succeed; what was the answer; if it failed, why.

Tools the agent needs

dig wrapper: queries authoritative servers. Returns structured output.

Cache lookup: checks local resolver caches. Catches stale-cache issues.

DNS-DB query: pulls records from the authoritative source for the zone. Compares with what the resolver returned.

Output classes

Resolved correctly. Most cases. Agent confirms and exits.

NXDOMAIN. Hostname does not exist. Agent reports; sometimes a typo, sometimes intentional.

Stale cache. Resolver returned an old answer. Agent flags; cache flush usually fixes.

Authoritative misconfiguration. The zone has a problem. Escalate to the team that owns the zone.

Why this is project zero

DNS issues are common and well-understood. The team has prior runbooks; the agent is a translation, not a from-scratch design.

Failure modes are bounded. The worst the agent can do is return a wrong classification; humans verify before acting.

Success is satisfying. "The agent classified the issue correctly in 3 seconds" produces team buy-in.

What to graduate to next

After DNS, try certificate-expiry investigation. Similar bounded scope, similar read-only signals.

After that, try external-service-status checks. The pattern (probe, classify, report) is common across many SRE problems.

By the third agent, the team has internalised the agent-building pattern. Subsequent agents come faster.