nslookup

What is this?

The nslookup.io MCP server gives any MCP-capable AI assistant (Claude, ChatGPT, Cursor, Windsurf, …) direct access to nslookup.io's DNS, certificate, security, and monitoring tools. Ask in plain language — "Run a DNS health check on github.com" or "Which of my SSL certificates expire soonest?" — and the assistant calls the right tool for you.

23 tools total, in two groups:

• 17 public tools — DNS, SSL, security, GEO, and domain-intelligence lookups that work anonymously, with no account and no API key.
• 6 my_ account tools — read your own nslookup.io monitoring account (uptime, DNS, WHOIS, SSL, propagation, BIMI/VMC monitors). These are always listed but require signing in.

Jump to Connect to get set up, or the Tool reference for the full list.

Connect

There are two ways to connect. Pick one — see the note below.

	Hosted (recommended)	Local (npx / stdio)
Endpoint	https://mcp.nslookup.io/mcp	npx -y @nslookup-io/mcp-server
Transport	Streamable HTTP (remote)	stdio (runs on your machine)
Install	Nothing to install	Requires Node.js 18+
17 public tools	✅ Anonymous	✅ Anonymous
6 my_ account tools	✅ Browser sign-in (OAuth) on first use	❌ Not available locally — use the hosted connector

Use the hosted endpoint if you want your own monitoring data — it's the only mode where the my_ account tools sign in for you, right in the browser. The local mode is great for the 17 public tools with zero setup.

Connect for your account (portal) tools

To use your own NsLookup.io monitoring data (the 6 my_ account tools), add the hosted connector and sign in. There is no API key — authentication is a one-time browser sign-in (OAuth) against your nslookup.io account.

Claude Code (CLI)

claude mcp add --transport http nslookup https://mcp.nslookup.io/mcp

Then invoke an account tool — e.g. ask "show my monitoring overview". A browser sign-in window appears; after you sign in once, all 6 my_ tools work (the client remembers it).

Claude Desktop / claude.ai — add a custom connector with URL https://mcp.nslookup.io/mcp, then sign in when prompted.

.mcp.json (project) or any HTTP-capable client:

{ "mcpServers": { "nslookup": { "type": "http", "url": "https://mcp.nslookup.io/mcp" } } }

The 17 public tools work immediately over this same endpoint — you only sign in the first time you reach for your own data.

Hosted (recommended)

The hosted endpoint is a remote Streamable-HTTP server. Public tools work immediately; the first time you call a my_ tool, an OAuth-capable client opens a browser window to sign in to your nslookup.io account (see Signing in).

Claude Code (CLI)

claude mcp add --transport http nslookup https://mcp.nslookup.io/mcp

Claude Desktop / claude.ai (custom connector)

1. Open Settings → Connectors
2. Click Add custom connector
3. Name: nslookup — URL: https://mcp.nslookup.io/mcp
4. Click Add

Or drop it into an .mcp.json (project) / your client's MCP config:

{
  "mcpServers": {
    "nslookup": {
      "type": "http",
      "url": "https://mcp.nslookup.io/mcp"
    }
  }
}

ChatGPT

1. Open Settings → Connected apps (or Tools & integrations)
2. Click Add custom integration / Add MCP server
3. Name: nslookup — URL: https://mcp.nslookup.io/mcp
4. Save

Cursor / Windsurf (and any HTTP-capable client)

Add to your MCP config (.cursor/mcp.json, ~/.codeium/windsurf/mcp_config.json, etc.):

{
  "mcpServers": {
    "nslookup": {
      "type": "http",
      "url": "https://mcp.nslookup.io/mcp"
    }
  }
}

Local (npx / stdio)

Runs the server on your machine over stdio. Public tools only — all 17 public tools work with no auth. For your own monitoring data (the my_ account tools), use the hosted connector and sign in — the account tools are not available on the local transport.

Claude Code (CLI)

# Global (all projects)
claude mcp add nslookup --scope user -- npx -y @nslookup-io/mcp-server

# Or for a single project
claude mcp add nslookup --scope project -- npx -y @nslookup-io/mcp-server

Claude Desktop — add to claude_desktop_config.json:

{
  "mcpServers": {
    "nslookup": {
      "command": "npx",
      "args": ["-y", "@nslookup-io/mcp-server"]
    }
  }
}

Cursor (.cursor/mcp.json) / Windsurf (~/.codeium/windsurf/mcp_config.json):

{
  "mcpServers": {
    "nslookup": {
      "command": "npx",
      "args": ["-y", "@nslookup-io/mcp-server"]
    }
  }
}

⚠️ Use only ONE nslookup entry

Configure either the hosted entry or the local entry — not both. If two MCP servers named nslookup are registered at once (e.g. a hosted connector plus a local npx entry), tool calls can route to the wrong server and behave unpredictably. Pick the mode you want and remove the other.

Signing in

• 17 public tools — no account, no key, nothing to sign in for. They call public, stateless, no-auth endpoints.
• 6 my_ account tools — read your private monitoring data, so they require sign-in:
  • Hosted endpoint → browser OAuth. The server is an OAuth 2.1 resource server. Calling a my_ tool without credentials returns a 401 with a WWW-Authenticate challenge, and OAuth-capable clients (Claude web/desktop, Claude Code, …) then walk you through a browser sign-in against the nslookup.io identity provider (Keycloak). There is no API key — sign in once and the client remembers it. Everything else keeps working anonymously — you only sign in when you first reach for your own data. See Connect for your account (portal) tools.

Tool reference

Public tools (17 — anonymous)

DNS

Tool	Description
dns_lookup	Look up all common DNS records (A, AAAA, NS, MX, TXT, CNAME, SOA) for a domain
dns_record	Look up a specific DNS record type — supports all 53 types (HTTPS, DNSKEY, TLSA, SPF, etc.)
dns_propagation	Check DNS propagation across 18+ global servers (Cloudflare, Google, Quad9, regional, authoritative)
webservers	Get IPv4 and IPv6 addresses for a domain
dns_change_review	Review proposed DNS changes before applying them: diff vs current DNS, rule-based findings with fixes, and a 0–100 risk score

Domain intelligence

Tool	Description
rdap_lookup	Registration data (RDAP) for an IP, AS number, or domain — owner org, network range, RIR, contacts, dates
hosting_report	Who hosts a website: hosting provider, CDN/proxy, DNS provider, mail servers, server location, SSL issuer
status_page	Read a public status page (by slug or custom domain): overall status, components, active incidents

DNS health & security

Tool	Description
dns_health	Run a DNS health audit (39 checks across DNSSEC, MX, hygiene, TTL, nameservers, CAA, operational maturity) with severity-weighted scoring
ssl_certificate	Check SSL/TLS certificate — issuer, expiry, chain validity, cipher strength, SAN domains, TLS version
bimi_vmc	Check BIMI record and VMC (Verified Mark Certificate) — logo URL, trademark info, certificate expiry
bimi_check	Check only the BIMI DNS record (faster — skips the VMC certificate fetch)
security_scan	Scan a domain for security issues — SPF/DKIM/DMARC, cookie security, DNS misconfigurations
domain_scanner	Scan a domain's email security posture (SPF, DKIM, DMARC, BIMI) with per-indicator scores
uptime_check	One-time HTTP uptime check — status, response time, HTTP status code
uptime_check_multi	Check if a site is up from 7 global locations — Amsterdam, Sydney, London, Frankfurt, Delhi, Warsaw, South Carolina

GEO (AI readiness)

Tool	Description
geo_checker	Check a domain's GEO (Generative Engine Optimization) score — AI crawler access, structured data, entity signals, content extractability, and prioritized recommendations

Account tools (6 — require sign-in)

These my_ tools read your own nslookup.io monitoring account. They are always listed but require signing in to call.

Tool	Description
my_overview	Account health snapshot — aggregated 0–100 score with per-subsystem breakdown, plus your limits/quota
my_monitors	List all your monitors across every type (uptime, API, DNS, WHOIS, propagation, certificates, VMC)
my_incidents	Open (or all recent) incidents across all monitoring types, with a per-status/per-source summary
my_uptime_history	Uptime + response-time history for one monitor (by id or URL) over a configurable window
my_dns_changes	Recent DNS changes on your monitored domains with their risk reviews (0–100 score, severity counts)
my_certificates	SSL certificate expiry overview — alert-level counts and certificates sorted by soonest expiry

Supported DNS record types

A, AAAA, AFSDB, APL, AXFR, CAA, CDNSKEY, CDS, CERT, CNAME, CSYNC, DHCID, DLV, DNAME, DNSKEY, DS, EUI48, EUI64, HINFO, HIP, HTTPS, IPSECKEY, IXFR, KEY, KX, LOC, MX, NAPTR, NS, NSEC, NSEC3, NSEC3PARAM, NXT, OPENPGPKEY, OPT, PTR, RP, RRSIG, SIG, SMIMEA, SOA, SPF, SRV, SSHFP, SVCB, TA, TKEY, TLSA, TSIG, TXT, URI, ZONEMD

DNS servers

cloudflare, google, quad9, opendns, authoritative, and regional servers in South Africa, Australia, India, Netherlands, Canada, USA, Brazil, Ukraine, Russia.

Configuration

Environment Variable	Default	Description
NSLOOKUP_API_URL	https://www.nslookup.io	Base URL for the nslookup.io API
MCP_RESOURCE_URL	(request-derived)	(HTTP server) Explicit public origin of this resource server, used as the issuer/resource/authorization_servers value in OAuth metadata. When unset, the origin is derived from the incoming request (X-Forwarded-Proto + host). Set it to the fixed public URL (e.g. https://mcp.nslookup.io) in production.
KEYCLOAK_ISSUER	https://auth.nslookup.io/realms/nslookup-io	(HTTP server) OAuth token issuer used to validate sign-in JWTs (JWKS, issuer, exp)
KEYCLOAK_REALM_URL	(= KEYCLOAK_ISSUER)	(HTTP server) Keycloak realm base URL whose /.well-known/openid-configuration supplies the real authorization_endpoint/token_endpoint. For Keycloak this equals the issuer, so it rarely needs setting.
KEYCLOAK_CLIENT_ID	nslookup-io-mcp	(HTTP server) The pre-registered public Keycloak client id returned by the DCR shim. This client must already exist in the realm; no Keycloak DCR is enabled.

The hosted server is an OAuth 2.1 resource server: calling a my_ tool without credentials returns a 401 with a WWW-Authenticate challenge pointing at /.well-known/oauth-protected-resource, and OAuth-capable MCP clients then walk you through sign-in against the nslookup.io identity provider.

Sign-in works for DCR-only clients (Claude web/desktop, Claude Code) without enabling Keycloak DCR. The server also acts as its own OAuth authorization server for metadata: GET /.well-known/oauth-authorization-server returns an issuer equal to this server's own origin, with authorization_endpoint/token_endpoint pointing at the real Keycloak endpoints (fetched from the realm's OpenID configuration, cached with a static fallback) and registration_endpoint set to <origin>/register. Because the advertised issuer is this server, clients that compute {issuer}/register hit our Dynamic Client Registration (DCR) shim at POST /register (also POST /oauth/register), which ignores the submitted metadata and returns one pre-registered public Keycloak client (KEYCLOAK_CLIENT_ID, default nslookup-io-mcp) with token_endpoint_auth_method: "none", echoing back the requested redirect URIs. The browser sign-in and the PKCE code→token exchange happen directly on Keycloak. A public client with KEYCLOAK_CLIENT_ID must already exist in the realm; no Keycloak DCR endpoint is used or exposed.

Example prompts

Once connected, try asking your AI assistant:

• "What are the DNS records for github.com?"
• "Check the MX records for google.com"
• "Has the DNS propagated for my-domain.com A record?"
• "What IP addresses does cloudflare.com resolve to?"
• "Show me the DNSKEY records for example.com"
• "Check the SPF record for amazon.com"
• "Run a DNS health check on example.com"
• "What's the DNSSEC status of cloudflare.com?"
• "Check the DNS health score for my-domain.com — are there any critical issues?"
• "Check the SSL certificate for github.com"
• "Does google.com have a BIMI record?"
• "Run a security scan on example.com"
• "Is https://cloudflare.com up right now?"
• "Check if github.com is accessible from all global locations"
• "Check DNS propagation for example.com NS records across all global servers"
• "Check the GEO score for github.com"
• "Is example.com optimized for AI search engines?"
• "Which AI crawlers does cloudflare.com block?"
• "Who owns the IP 8.8.8.8?"
• "Look up registration data for AS13335"
• "Who hosts github.com?"
• "Review this DNS change for example.com before I apply it: ..."
• "Scan example.com's email security (SPF, DKIM, DMARC)"
• "Is the nslookup-io status page reporting any incidents?"

And once signed in to your nslookup.io account:

• "How healthy is my monitoring right now?"
• "List all my monitors — anything down or expiring?"
• "Do I have any open incidents?"
• "Show me the uptime history for https://myapp.com over the last 48 hours"
• "Any risky DNS changes on my domains recently?"
• "Which of my SSL certificates expire soonest?"

Feedback

We'd love to hear from you! At nslookup.io, we're building a fast, reliable, and free DNS lookup tool and monitoring platform for everyone — from developers and sysadmins to everyday internet users.

Your feedback is what helps us improve. Whether you've spotted a bug, have a feature idea, or just want to share your thoughts — we're listening. Contact us.

License

Apache 2.0