AS57976: the BLIZZARD network

AS57976 is an internet Autonomous System operated by BLIZZARD (the United States). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS57976?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS57976 was assigned to BLIZZARD by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS57976 currently announces 38 IPv4 block(s), totaling about 66 thousand addresses (66,048 in all), registered in the United States. Services from BLIZZARD are reached through these addresses.

What it means to see AS57976 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS57976. That means the other end sits on the BLIZZARD network (the United States). It can be legitimate — a cloud service, an ISP, a CDN — or an unexpected connection worth checking.

How to see every connection and network your devices reach

Tracing one connection's ASN at a time is tedious. Sentinela, by PC Monitor, maps the devices on your network, shows what is exposed to the internet and helps flag suspicious connections and devices — running on your Windows. Meet Sentinela.