// Tool
AS-SET Resolver
Resolve an AS-SET (or AS-macro) into its member ASNs via NLNOG's irrexplorer.nlnog.net API, which queries every public IRR (RADb, ARIN, RIPE, APNIC, ALTDB, etc.) in parallel. Each ASN is then enriched with org info from PeeringDB.
Accepts AS-SET names (must start with
AS-). For a plain ASN, use the BGP Looking Glass. Try:
Frequently Asked Questions
What is an AS-SET?
An AS-SET is a named group of autonomous systems (and other AS-SETs) defined in an Internet Routing Registry. Transit providers use it to build prefix filters for a customer and that customer’s downstreams.
Why does expanding an AS-SET matter?
The expanded member list determines which prefixes a provider accepts from you. A missing member means a downstream’s routes get filtered; a stale or bloated set can let unintended routes through.
What is IRRexplorer?
An NLNOG service that queries multiple IRR databases and RPKI to show the authoritative and conflicting data for an AS-SET, ASN, or prefix in one place.
