dns-lookup

dns-lookup is a skill for Claude Code, Codex from ofershap/mcp-server-dns. It costs 31 tokens per session (364 once invoked), scanned A, original, MIT.

A domain-information lookup tool for DNS records, reverse DNS, and WHOIS. DNS connects domain names to services such as websites and email; WHOIS provides domain registration details.

In plain words
What is it for?
Use it to look up A, AAAA, MX, TXT, NS, CNAME, SOA, SRV, or PTR records, inspect nameservers, resolve an IP address to a hostname, or query registration data.
Why use it?
It helps diagnose whether a domain points to the right servers and investigate email delivery, nameservers, or ownership information.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to look up A, AAAA, MX, TXT, NS, CNAME, SOA, SRV, or PTR records, inspect nameservers, resolve an IP address to a hostname, or query registration data.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ofershap/mcp-server-dns/dns-lookup
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add ofershap/mcp-server-dns --skill dns-lookup
Clone the repo
git clone --depth 1 https://github.com/ofershap/mcp-server-dns

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for dns-lookup

README.md
[![agentmods](https://agentmods.dev/badge/skills/ofershap/mcp-server-dns/dns-lookup/github.svg)](https://agentmods.dev/skills/ofershap/mcp-server-dns/dns-lookup)
Your own site
<a href="https://agentmods.dev/skills/ofershap/mcp-server-dns/dns-lookup"><img src="https://agentmods.dev/badge/skills/ofershap/mcp-server-dns/dns-lookup/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for dns-lookup

Your own site · 80×15
<a href="https://agentmods.dev/skills/ofershap/mcp-server-dns/dns-lookup"><img src="https://agentmods.dev/badge/skills/ofershap/mcp-server-dns/dns-lookup.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 364 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00031 $0.00364
Opus 5 $0.00015 $0.00182
Sonnet 5 $0.00006 $0.00073
Haiku 4.5 $0.00003 $0.00036

Measured 8d ago against content hash 087466a10ff9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

dns-lookup scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/dns-lookup/SKILL.md · 33 lines

What it actually says

DNS Lookup via MCP

Use this skill when you need to look up DNS records, perform reverse DNS, check WHOIS data, or verify nameservers. Zero auth required.

Available Tools

Tool What it does
dns_lookup Look up A, AAAA, MX, TXT, NS, CNAME, SOA, SRV, or PTR records
reverse_dns Reverse DNS (PTR) lookup on an IP address
resolve_all Resolve A, AAAA, MX, TXT, NS, CNAME in one call
check_nameservers Get nameserver (NS) records for a domain
whois Query WHOIS data (follows IANA referrals to registrar)

Workflow

  1. For general domain investigation: start with resolve_all to see everything at once
  2. For specific record types: use dns_lookup with the type parameter
  3. For IP investigation: use reverse_dns to find the hostname
  4. For domain ownership: use whois

Key Patterns

  • dns_lookup with type: "MX" is the go-to for email delivery debugging
  • resolve_all returns all common record types in one call — most efficient for initial investigation
  • whois follows IANA referrals automatically, so it works for any TLD
  • No API keys or auth needed — uses Node.js built-in DNS and public WHOIS servers
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 33 lines · 31 tokens per session scan A 087466a10ff9

Subscribe to this mod's changes

dns-lookup is a skill published in the GitHub repository ofershap/mcp-server-dns (3 stars, last pushed 6mo ago), licensed MIT. It adds 31 tokens to every session and 364 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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