I Built a DNS Expert Gem — Here's What It Actually Does

A Gemini Gems conversation interface showing DNS record configuration with a simple domain and server icon in clean minimal design
Part of the "My AI Team" Series — Each post covers one specific Gem I use daily. See the full series overview.

DNS is narrow, technical, and unforgiving. A misconfigured record can take down email delivery, break a website, or cause authentication failures that take hours to trace back to the root cause. I've been working with DNS professionally for over two decades. But I still built a DNS Expert Gem — because even experts benefit from a fast second opinion.

What Is a DNS Expert Gem?

It's a Gemini assistant configured specifically for DNS work. Record types, TTL strategy, zone file syntax, DNSSEC, SPF/DKIM/DMARC configuration, reverse DNS, split-horizon setups — it handles all of it at a technical level.

The narrow focus is intentional. A general-purpose AI gives you general-purpose DNS answers. This Gem gives you precise, syntax-correct answers for specific DNS scenarios.

Why I Built This Gem

DNS mistakes have real consequences and long propagation delays. Before I push a change to production, I want to verify my reasoning. Three situations drive most of my use:

  • Validating zone file changes before deployment — catching syntax errors or logic mistakes before they propagate
  • Debugging email delivery failures that trace back to SPF, DKIM, or DMARC misconfigurations
  • Explaining DNS behavior to colleagues or clients who need to understand why something is happening

For the third case, this Gem is particularly good — it can explain the same DNS concept at whatever level of depth I specify.

The Prompt I Use

Here's the core of my Gem's instructions:

You are my DNS expert with deep knowledge of DNS protocols, record types, zone management, DNSSEC, and email authentication records (SPF, DKIM, DMARC). When I ask DNS questions: - Work at a senior network engineer level — skip basics unless I ask - Validate zone file syntax and flag errors before I deploy - Explain propagation behavior and TTL implications accurately - Generate correct record syntax when I describe what I need - Flag anything that could cause email delivery failures or resolution problems My context: managing DNS for multiple domains, mix of authoritative and recursive resolvers, BIND and cloud DNS providers (Cloudflare, Route 53). Primary concerns: email deliverability and resolution reliability.

Real Examples — What I Actually Ask It

Some recent questions I've put to this Gem:

  • "Here's my SPF record. I'm adding a new mail relay — what does the updated record look like and am I close to the lookup limit?"
  • "I need a DMARC record that reports only, no enforcement yet. Generate the correct syntax."
  • "A domain I manage has an MX record pointing to a CNAME. Is that valid? Why are some resolvers rejecting it?"

For the SPF lookup limit question, it counted my current lookups, explained that SPF has a hard limit of 10 DNS lookups, showed me which mechanisms were consuming them, and suggested which to flatten into IP ranges. That kind of precise analysis takes real time to do manually.

Using It for Email Authentication Debugging

Email authentication failures — where a message gets rejected or marked as spam due to SPF/DKIM/DMARC misconfiguration — are among the most frustrating issues to debug. The error messages are often cryptic and the interactions between the three systems are non-obvious.

I paste in the email headers or the DNS records and ask the Gem to walk through what's happening. It explains the authentication chain clearly, identifies where it's breaking, and tells me exactly what to fix.

What It's Good At (and Where It Falls Short)

Good at:

  • Generating correct DNS record syntax for any record type
  • Validating SPF, DKIM, and DMARC configurations
  • Explaining propagation behavior and TTL strategy
  • Debugging email delivery failures from headers or DNS records

Where it falls short:

  • It cannot query live DNS — you need to paste in actual records or use dig/nslookup yourself
  • DNSSEC key management specifics are better verified against current RFC documentation
  • Provider-specific quirks (Cloudflare proxy behavior, Route 53 alias records) may need verification against current docs

Try It Yourself — Starter Prompt

If you want to build a similar Gem, here's a starting point:

You are my DNS expert. Validate zone file syntax and flag errors. Generate correct record syntax when I describe what I need. Explain SPF, DKIM, and DMARC configurations accurately. Flag anything that could cause email delivery failures. My context: [your DNS providers, primary concerns, technical level]

Paste this into a new Gem at gemini.google.com, add your context, and test it by pasting in a real DNS record you want to verify.

My AI Team Series

Related Posts

Sources & Further Reading

Do you manage DNS for your own domains? What's the most frustrating DNS issue you've had to debug? Let me know in the comments.

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