What Is My ISP?

What an ISP is

An internet service provider is the company that carries traffic between your home, phone or office and the rest of the internet. It gives your connection a public IP address, routes your packets, and is recorded in the public address registries as the holder of that address block. So when you ask "who is my ISP", the useful answer is the name of the network your connection sits on right now, which is what the table above reads.

ISP, organisation and ASN are three different things

The same connection is described at three levels, and they often disagree:

• ISP is the provider name published with the address range.
• Organisation is whoever the range is assigned to. On a home line it usually repeats the ISP name. On a business line it is often the customer's own company, because the carrier delegated that block to them.
• ASN, the autonomous system number, identifies the network that announces your address range to the global routing table. AS7922 is Comcast, AS15169 is Google. The number is stable and unambiguous, which makes it the most reliable field of the three.

A shop on a business line can show organisation "Smith Hardware", ISP "Comcast Cable" and AS7922 all at once. Nothing is wrong there. It is one network, described by three records.

How we work out your ISP

We take the public IP address your connection presents, find the block it belongs to, and read the records published for that block: the allocation held by the regional internet registry for your part of the world (ARIN, RIPE NCC, APNIC, LACNIC or AFRINIC) and the routing origin for the prefix. An ISP lookup reads public network data, the same data every website you visit can read about you. It never touches your account, your bill or anything stored in your browser.

Reverse DNS adds one more clue. Many providers name each address, for example c-73-12-0-1.hsd1.ca.comcast.net, which usually names the provider and sometimes the region. An address with no PTR record is common and means nothing is wrong with your connection.

Why the name may not be the company you pay

The billing relationship and the network are separate. You can see a different name when:

• Your provider resells capacity from a larger carrier, so the carrier owns the addresses.
• You are on a mobile virtual network operator, where the radio network and addresses belong to the host carrier.
• A VPN or proxy is on, so the provider shown is the VPN operator's data centre.
• Your provider uses carrier-grade NAT and shares one public address across many subscribers, which pushes the visible address to a regional block.
• You are on a company, campus or hotel network that holds its own address space.

Connection types

Residential or business covers ordinary fixed lines. An allocation record rarely separates the two, so this page shows them together rather than guessing. Mobile means the network name matches a mobile carrier, so the traffic is coming over a phone or mobile broadband. Hosting or data centre means the block belongs to a cloud, hosting or content-delivery network, which is what you see for servers, VPN exit nodes and scrapers. Public DNS resolver is shown for well-known resolver addresses such as 8.8.8.8, which are not subscriber lines at all.

Tier 1, Tier 2 and Tier 3 providers

Tier 1 networks reach the whole internet without paying anyone for transit. They swap traffic with each other as peers, which is what defines the tier. AT&T, Lumen, Telia, Arelion and NTT sit here, and most people never buy service from them directly.

Tier 2 networks peer where it suits them and buy transit from Tier 1 networks for the rest. Most national and regional providers are Tier 2, including the cable and fibre companies that serve homes.

Tier 3 networks buy all of their connectivity and resell it locally. Small-town providers, wireless operators and building-wide services usually fall here. The tier affects routing and cost, not whether your connection works.

How to change what sites see

Turn on a VPN and sites see the VPN operator's provider and location instead of yours. Switch a laptop to a phone hotspot and the mobile carrier appears. Restart your router if your provider hands out dynamic addresses and you want a different one from the same pool. If you need a fixed address or a business record, ask your provider about a static IP or a business plan, which is the only route that changes the registry entry itself.

What this page cannot tell you

• Your account number, plan or bill.
• Your name or your street address.
• Your connection speed or data cap.
• Which building or apartment you are in. Location is an estimate for the address block, often the provider's regional hub.
• Anything about other people sharing the same public address behind CGNAT.