Enter an IP address or domain to find its autonomous system.
101IP identifies the autonomous system (ASN) of any IP address or domain. An ASN is a unique number assigned to an ISP, hosting provider or large organisation's network.
Enter the domain name (e.g. google.com) in the search field on the /asn/ page. The tool automatically resolves the domain to an IP address via DNS, then looks up the corresponding autonomous system number, network owner and country of registration. Results are returned in real time.
Yes, 101IP supports both IPv4 and IPv6. Enter an IPv6 address (for example, 2a00:1450:4010:c0c::1a) in the input field and the tool will identify its autonomous system and network prefix. Data is sourced from global Regional Internet Registries including RIPE and ARIN.
An ASN (Autonomous System Number) is a unique identifier assigned to a large network under a single administrative authority, such as an ISP or hosting provider. A subnet (prefix) is a specific block of IP addresses within that network, announced via BGP. A single ASN can manage hundreds of different prefixes — our tool shows all prefixes associated with the found ASN.