domains-dns

domains-dns is a skill for Claude Code, Codex from ericrisco/rsc-harness. It costs 87 tokens per session (2,573 once invoked), scanned A, original, MIT.

A guide to connecting a domain name to a host and serving it over valid HTTPS. It covers DNS, the system that maps names to servers, including A, AAAA, CNAME, MX, TXT, and CAA records, plus nameservers and TLS certificates.

In plain words
What is it for?
Use it to delegate nameservers, create or correct DNS records, point apex and www addresses at a service, enable renewing TLS, and move DNS without downtime.
Why use it?
It gives a clear order for diagnosing domains that do not resolve or HTTPS that fails. Checking registration, delegation, records, and then certificates prevents chasing certificate errors caused by an incorrect DNS target.

Skill for Claude CodeCodex

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

Good fit Use it to delegate nameservers, create or correct DNS records, point apex and www addresses at a service, enable renewing TLS, and move DNS without downtime.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ericrisco/rsc-harness/domains-dns
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 ericrisco/rsc-harness --skill domains-dns
Clone the repo
git clone --depth 1 https://github.com/ericrisco/rsc-harness

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 domains-dns

README.md
[![agentmods](https://agentmods.dev/badge/skills/ericrisco/rsc-harness/domains-dns/github.svg)](https://agentmods.dev/skills/ericrisco/rsc-harness/domains-dns)
Your own site
<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/domains-dns"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/domains-dns/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 domains-dns

Your own site · 80×15
<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/domains-dns"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/domains-dns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 87 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,573 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high YARA Match · line 52
    YARA rule matched a known malware signature (reverse shell, backdoor, ransomware, C2 framework, or info stealer).
    Fix: Remove the malware payload or compromised file entirely. Investigate how it entered the skill and audit all other artifacts for additional indicators of compromise.
How audits are shown
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 $0.00087 $0.02573
Opus 5 $0.00044 $0.01287
Sonnet 5 $0.00017 $0.00515
Haiku 4.5 $0.00009 $0.00257

Measured 6d ago against content hash d3367b3296f4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

domains-dns 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 6d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/verify.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

- **Serve the full chain, not the leaf.** A leaf-only config validates in browsers (they cache intermediates) but fails on `curl` and mobile — the classic "works on my machine" TLS bug. Serve `fullchain.pem`.
skills/domains-dns/SKILL.md · 132 lines

How it starts

The opening of the file, as written. The whole thing — 132 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Domains & DNS

You set up a name end to end: register or delegate it, write the records, and serve valid HTTPS. Almost every "my domain doesn't work" report is one of a handful of recurring mistakes. This skill names them and gives you paste-ready records plus the commands to prove they took.

Resolution order is debug order

A request resolves in one direction. Diagnose in the same direction, top-down, because the bug is almost always at the layer the user is not looking at.

  1. Name — does the domain exist and is it registered/not expired? (whois)
  2. Delegation — do the registrar's nameservers point at the DNS provider that actually holds the zone? (dig NS)
  3. Records — does the authoritative zone return the right A/AAAA/CNAME/ALIAS/MX/TXT/CAA? (dig @<authoritative-ns>)
  4. TLS — does the served chain validate and is it unexpired? (openssl s_client)

Rule: never debug TLS before you've confirmed the record resolves to the box you think it does — a cert error is often a record pointing at the wrong host. Query authoritative nameservers, not your laptop's cache, or you'll chase a stale answer for an hour.

Where the DNS lives

Pick one authoritative provider and keep the whole zone there. Splitting a zone across two providers (some records at the registrar, some at Cloudflare) is the source of "it works for me but not for them" — resolvers see whichever NS set answered.

Host the zone at Choose when Why
Registrar DNS (GoDaddy, Namecheap, Porkbull) Tiny static site, one or two records One vendor, fewer logins; weak APIs and slow propagation
Dedicated DNS (Cloudflare, DNSimple) Most cases; want CNAME flattening + fast edits Apex flattening, low TTL edits, good API; see ../cloudflare/SKILL.md
Cloud DNS (Route 53, Cloud DNS) Already all-in on AWS/GCP and want alias-to-LB Native alias records to cloud load balancers
Host-managed (Vercel, Netlify) The host is the only thing the domain serves Auto-TLS + apex flattening handled for you; see ../vercel/SKILL.md

Read the full file on GitHub · 132 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago First seen · 132 lines · 87 tokens per session scan A d3367b3296f4

Subscribe to this mod's changes

domains-dns is a skill published in the GitHub repository ericrisco/rsc-harness (78 stars, last pushed today), licensed MIT. It adds 87 tokens to every session and 2,573 once invoked, about $0.0004 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 2026-09-03.

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