An inactive ASN (Autonomous System Number) is an ASN that is no longer used for routing internet traffic.
Autonomous Systems (AS) are networks or groups of IP networks managed by a single organization. They use ASNs to identify themselves globally on the internet.
Inactive ASNs no longer participate in routing, meaning they are not announcing or receiving any IP prefixes. They might still exist in records, but are not operational on the internet.
Reasons an ASN may become inactive include:
- Decommissioning of the AS: The organization that owns the ASN might no longer exist or no longer use that ASN.
- Reassignment: The ASN could be reallocated or transferred to another entity.
- Merger or Acquisition: When companies merge, their networks may be consolidated, making one or more ASNs unnecessary.
- Revocation by RIRs: Regional Internet Registries (RIRs) may revoke an ASN if it has been unused or abandoned for a long period.
Are inactive ASNs ever reactivated?
Yes, inactive ASNs can sometimes be reactivated. If an organization that previously owned the ASN becomes active again or if the ASN is transferred to another entity, it can resume operations.
This ASN was inactive for some time, then it was reactivated: https://ipinfo.io/AS329017
How does the deactivation of an ASN affect internet routing?
When an ASN is deactivated, it stops announcing routes via BGP (Border Gateway Protocol), which means its prefixes (IP address ranges) are no longer advertised to other networks. The deactivated ASN and its associated prefixes will eventually be removed from global BGP routing tables. IP addresses associated with the ASN will become unreachable unless transferred to another active ASN.
What happens to the IP addresses associated with an inactive ASN?
IP addresses associated with an inactive ASN can be reassigned or reallocated. They can be transferred to another ASN, returned to the RIR or become dormant.