AS12257: the EMC-AS12257 network

AS12257 is an internet Autonomous System operated by EMC-AS12257 (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 AS12257?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS12257 was assigned to EMC-AS12257 by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS12257 currently announces 29 IPv4 block(s), totaling about 16.1 thousand addresses (16,128 in all), registered in the United States. Services from EMC-AS12257 are reached through these addresses.

What it means to see AS12257 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS12257. That means the other end sits on the EMC-AS12257 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.