Hostname

o21.nl

Last fetched Sat, 25 Jul 2026 23:15:24 GMT

o21.nl resolves to 1 IPv4 address operated by AS20559 in NL. WHOIS lists registrar:nubix b.v. as the registrar.

Nutrition Label

Resolution chain

o21.nl resolves to 1 distinct IPv4 address via WhisperGraph DNS data. Each row links to the IP, prefix, and announcing ASN.

IP	Prefix	ASN	Operator	Country
31.200.209.198	31.200.208.0/21	AS20559	—	NL

WHOIS identity

Registrar: registrar:nubix b.v.
Organization: —
Contact emails: —

Subdomains

3 observed subdomains of o21.nl.

Subdomain
mail.o21.nl
postmaster.o21.nl
www.o21.nl

Web-graph footprint

Distinct hostnames that link to or from o21.nl in the public web crawl.

32 sites linked to from this hostname.

Sample outbound links

Threat posture

History

Mail and authentication

MX records

o21-nl.mail.protection.outlook.com

SPF policy

4 SPF mechanisms authorising senders for o21.nl.

Mechanism	Target
SPF_A	o21.nl
SPF_INCLUDE	spf.protection.outlook.com
SPF_IP	31.200.209.198
SPF_MX	o21.nl

Pivot deeper into the graph from o21.nl.

Cypher and MCP

Reproduce the resolution chain directly against graph.whisper.security:

MATCH (h:HOSTNAME {name: "o21.nl"})-[:RESOLVES_TO]->(ip:IPV4)
      -[:ANNOUNCED_BY]->(ap:ANNOUNCED_PREFIX)
      -[:ROUTES]->(asn:ASN)-[:HAS_NAME]->(n:ASN_NAME)
RETURN ip.name AS ip, ap.name AS prefix, asn.name AS asn, n.name AS operator
LIMIT 20

Or query Whisper from your own LLM workflow via the Whisper MCP server.