An autonomous system number (ASN) is a unique identifier assigned to each network on the internet. It is used to identify the network and to route traffic between networks. To check the ASN of a network, you can use a variety of online tools, such as the ASN Lookup tool from ARIN. Simply enter the IP address or domain name of the network you want to check, and the tool will return the ASN.
ASNs are important for a number of reasons. First, they allow networks to be uniquely identified on the internet. Second, they help to route traffic between networks. Third, they can be used to track the path of traffic across the internet.