WHOIS / RDAP shows registrar, term, status and holder of a domain, IP or AS number. IP Info returns reverse DNS, AS, prefix, country and network owner.

Two tools in the Netzwerk (network) category answer the question “who owns this?”: WHOIS / RDAP for domains, IP networks and autonomous systems, and IP-Info for a single IP address. Both require a license.

WHOIS / RDAP

In the Domain, IP oder AS field, enter:

Input	Example	Result
domain	`inwendo.de`	the domain’s registration
IP address	`1.1.1.1`	the IP network the address belongs to
AS number	`AS13335`	the autonomous system

RDAP first

The app prefers RDAP, the structured successor of WHOIS. It takes the responsible server from IANA’s directories. For a subdomain it works its way up to the registered domain, so www.example.com becomes example.com.

For a domain, the Domain table shows registrar, holder (if public), status, registered, expires, changed, name servers, DNSSEC and abuse contact. The full RDAP response is under Rohdaten (raw data).

Classic WHOIS for .de and others

Many country-code TLDs, including .de, don’t offer RDAP. The app then reports „Kein RDAP für .de“ (no RDAP for .de) and uses classic WHOIS over port 43 instead: first whois.iana.org, then the server IANA refers to. The recognized fields appear in a table, the complete response under Rohdaten.

DENIC only returns a little data via WHOIS. Holder and contacts aren’t public for privacy reasons. The app points this out.

WHOIS over port 43 isn’t possible in the web version, so you can’t look up domains without RDAP there.

Domain findings

Finding (as shown in the app)	Meaning and what to do
Registriert bei …	Registered with …: OK.
… ist nicht registriert	The domain is not registered (RDAP 404 or WHOIS reports no match).
Läuft in … Tagen ab	Expires in under 30 days: check that auto-renewal is active at the registrar.
Registrierung abgelaufen am …	Registration expired. Renew at the registrar right away.
Domain ist gesperrt (Hold)	The domain is on hold and not published in DNS. Sort it out with the registrar; often unconfirmed holder data or an unpaid invoice.
Domain steht zur Löschung an	The domain is pending deletion. Restore it at the registrar right away.
Transfersperre aktiv	Transfer lock active: OK, protects against an unwanted transfer.
Keine Transfersperre	Note: enable a transfer lock (`clientTransferProhibited`) at the registrar.
Laut Registry nicht mit DNSSEC signiert	Note: not DNSSEC-signed according to the registry.

For IP addresses, the IP-Netz (RDAP) table shows network name, range, CIDR, type, country, holder and abuse contact. For AS numbers, Autonomes System shows name, country, holder and abuse contact.

IP Info

IP-Info gathers the key facts about an address. In the IP oder Hostname field, enter an IPv4 or IPv6 address, for example 1.1.1.1, or a hostname. A hostname is resolved first and the first address used. Further addresses are listed in the finding.

The IP-Adresse table shows:

Field	Source
Reverse DNS	the address’s PTR record
AS	number and name of the autonomous system announcing the address
Präfix (BGP)	the announced network
Land, Registry, Zugeteilt	country, registry and allocation date from the Regional Internet Registry

The app gets AS, prefix and country via DNS from Team Cymru’s service. Below that is the IP-Netz (RDAP) table with network owner and abuse contact.

Findings

Finding	Meaning
AS… · prefix	OK, the address is announced on the internet.
Kein PTR-Record	No PTR record. A problem for mail servers, see MX Lookup.
Kein AS gefunden	No AS found: the prefix isn’t announced on the internet.
Mehrere Ursprungs-AS (MOAS)	The prefix is announced by several AS.
Private oder reservierte Adresse	There’s no public AS or holder data for private or reserved addresses.
Missbrauch melden an …	The network operator’s abuse address, for example to report spam or attacks from this IP.

WHOIS / RDAP and IP Info