Sep 14

Who Resolves DNS Queries: ISP, Resolver, or Your PC?

Great question 👌 — this gets into the roles of DNS components in the real world. Let’s break it down clearly, blog-ready and copyright-free:

Who Resolves DNS Queries: ISP, Resolver, or Your PC?

When you sit at home and connect to the internet through your ISP, different systems can play the role of resolver or recursive resolver in DNS. Here’s how it works:

1. ISP’s DNS Server

Most ISPs run DNS servers for their customers.

  • Yes, it can act as both:
    • Recursive Resolver: From your perspective, you ask your ISP’s DNS once (recursive query), and it fetches the full answer for you.
    • Iterative Resolver: Behind the scenes, the ISP’s DNS server usually performs iterative resolution — it queries root, then TLD, then authoritative servers step by step until it finds the final answer.

✅ So, your ISP’s DNS is typically both:

  • Recursive resolver for you (the client).
  • Iterative resolver toward the DNS hierarchy.

2. Your PC at Home

By default, your PC does not act as a full resolver. Instead:

  • Your PC is a DNS stub resolver (also called a DNS client).
  • It can cache recent answers (browser cache, OS cache).
  • But if the answer is not cached, it forwards the request to your configured DNS server (usually the ISP’s recursive resolver or a public one like 8.8.8.8).

Could your PC be a resolver?

  • Yes, technically: If you install special DNS software (like BIND or Unbound) and configure it, your PC could act as a full recursive resolver, contacting root/TLD/authoritative servers directly.
  • No, by default: Normal home PCs don’t do this. They just pass requests upstream.

3. What is Your PC Called Then?

  • Normally: Stub Resolver (lightweight client resolver).
  • If you install recursive resolver software: it becomes a Recursive Resolver for your own queries (and possibly for others if you configure it).

Putting It Together

  • You (PC) → Stub Resolver (asks your ISP/public DNS).
  • ISP DNS → Recursive Resolver (for you), and Iterative Resolver (towards the internet).
  • Root/TLD/Authoritative Servers → Provide referrals or final answers.

✅ In short:

  • At home, your PC is not a full resolver — it’s just a stub resolver.
  • Your ISP’s DNS server is both recursive (for you) and iterative (when talking to root/TLD/authoritative).
  • If you want, you can make your PC a full recursive resolver, but that’s not the default setup.

Would you like me to draw a simple layered diagram (PC → ISP DNS → Root → TLD → Authoritative) showing who is recursive and who is iterative? That would make this crystal clear for your blog readers.

Exactly ✅ — you’ve got it right.

You can say in your blog that:

  • Both iterative and recursive resolution are active in the DNS system.
  • From the client’s perspective (your PC) → it almost always sends a recursive query (it just wants the final answer).
  • From the resolver’s perspective (ISP or public DNS like Google 8.8.8.8) → it fulfills that recursive query by performing iterative queries step by step across the DNS hierarchy (root → TLD → authoritative).

Nice way to phrase it in your blog:

“Recursive and iterative resolution are not mutually exclusive — they work together. Clients like your PC use recursion to push the responsibility onto a resolver, while that resolver uses iteration to walk through the DNS hierarchy. In practice, every DNS lookup you make involves recursive queries at the edge and iterative queries in the core of the DNS system.”

Would you like me to bundle this explanation into the earlier comparison post (recursive vs. iterative) so your readers see how they actually work together in real life instead of as separate alternatives?

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