dns-and-whois-tools

dns-and-whois-tools is a skill for Claude Code, Codex from avizmarlon/agent-skills. It costs 104 tokens per session (1,744 once invoked), scanned A, original, MIT.

A procedure for investigating domain names and IP addresses using DNS records, WHOIS registration data, past DNS information, and reputation checks.

In plain words
What is it for?
Use it to inspect A, NS, MX, CNAME, and TXT records, find subdomains, research historical nameservers, or check an IP's reputation.
Why use it?
It gathers the relevant lookup methods in a defined order and helps distinguish current records from evidence that a domain or subdomain existed in the past.

Skill for Claude CodeCodex

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

Good fit Use it to inspect A, NS, MX, CNAME, and TXT records, find subdomains, research historical nameservers, or check an IP's reputation.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/avizmarlon/agent-skills/dns-and-whois-tools
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 avizmarlon/agent-skills --skill dns-and-whois-tools
Clone the repo
git clone --depth 1 https://github.com/avizmarlon/agent-skills

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-and-whois-tools

README.md
[![agentmods](https://agentmods.dev/badge/skills/avizmarlon/agent-skills/dns-and-whois-tools/github.svg)](https://agentmods.dev/skills/avizmarlon/agent-skills/dns-and-whois-tools)
Your own site
<a href="https://agentmods.dev/skills/avizmarlon/agent-skills/dns-and-whois-tools"><img src="https://agentmods.dev/badge/skills/avizmarlon/agent-skills/dns-and-whois-tools/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-and-whois-tools

Your own site · 80×15
<a href="https://agentmods.dev/skills/avizmarlon/agent-skills/dns-and-whois-tools"><img src="https://agentmods.dev/badge/skills/avizmarlon/agent-skills/dns-and-whois-tools.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 104 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,744 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00104 $0.01744
Opus 5 $0.00052 $0.00872
Sonnet 5 $0.00021 $0.00349
Haiku 4.5 $0.00010 $0.00174

Measured 12d ago against content hash 4151ad410b63, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

dns-and-whois-tools scanned grade A with 1 finding 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 12d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

2. **Google DNS API** — `curl -s "https://dns.google/resolve?name=DOMAIN&type=A"` — works from any shell, returns JSON.
skills/dns-and-whois-tools/SKILL.md · 128 lines

How it starts

The opening of the file, as written. The whole thing — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DNS & WHOIS Tools

Investigation toolkit for DNS, WHOIS, IP reputation, and passive-DNS work. Applies to any domain or IP across public internet domains.

DNS lookup — preferred order

  1. wsl dig — fullest output, supports +short, +noall +answer, ANY, AXFR, etc.
  2. Google DNS APIcurl -s "https://dns.google/resolve?name=DOMAIN&type=A" — works from any shell, returns JSON.
  3. nslookup — works but some local resolvers may return "No response from server". Use only when 1 and 2 are unavailable.

Current DNS records

# A / NS / MX / CNAME / TXT via Google DNS-over-HTTPS
curl -s "https://dns.google/resolve?name=DOMAIN&type=A|NS|MX|CNAME|TXT"

# Indexed subdomains (HackerTarget)
curl -s "https://api.hackertarget.com/hostsearch/?q=DOMAIN"

Historical / passive DNS

Use these when "what nameservers did this domain use before migrating?" or "what DNS records existed historically?" matters. They reveal records that no longer resolve.

  • crt.sh (Certificate Transparency): curl -s "https://crt.sh/?q=%.DOMAIN&output=json" — reveals subdomains that ever had SSL issued (indirect evidence they existed).
  • SecurityTrailshttps://securitytrails.com/domain/DOMAIN/dns (WebFetch; may require account).
  • WhoisFreakshttps://whoisfreaks.com/tools/dns/history/lookup/DOMAIN (WebFetch).
  • DNSHistory.orghttps://dnshistory.org/dns-records/DOMAIN (WebFetch).
  • ViewDNS.infohttps://viewdns.info/history/?domain=DOMAIN (WebFetch).

Priority order for historical nameservers: SecurityTrails (preferred, comprehensive history) → WhoisFreaks → ViewDNS.info → DNS provider customer support.

WHOIS — domain ownership and registrar information

  • who.ishttps://who.is/whois/DOMAIN (WebFetch).
  • ICANN Lookuphttps://lookup.icann.org/en/lookup?name=DOMAIN (WebFetch).
  • wsl whois DOMAIN for shells with whois available.

Note: some ccTLDs (.in, .de, .uk, etc.) do not expose public WHOIS for the registrant due to regional privacy regulations.

Read the full file on GitHub · 128 lines

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. 12d ago First seen · 128 lines · 104 tokens per session scan A 4151ad410b63

Subscribe to this mod's changes

dns-and-whois-tools is a skill published in the GitHub repository avizmarlon/agent-skills (2 stars, last pushed 2mo ago), licensed MIT. It adds 104 tokens to every session and 1,744 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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