Network Overview
| ASN | AS5400 |
| Organization | British Telecommunications PLC |
| Announced IPv4 ranges | 64 |
| Total IPv4 addresses | 713,472 |
Sample IP Ranges Announced by AS5400
| Range Start | Range End | Lookup |
|---|---|---|
31.95.0.0 |
31.95.7.255 |
Details → |
31.95.14.0 |
31.95.31.255 |
Details → |
31.95.48.0 |
31.95.56.255 |
Details → |
31.95.64.0 |
31.95.71.255 |
Details → |
31.95.96.0 |
31.95.127.255 |
Details → |
31.95.160.0 |
31.95.175.255 |
Details → |
What Is an Autonomous System?
An autonomous system (AS) is a collection of IP networks operated by a single organization - an ISP, cloud provider, enterprise, or university - that shares a common routing policy. Each AS is identified by a unique AS number (ASN) and exchanges routing information with other systems using the BGP protocol.
Knowing which ASN an IP belongs to reveals who actually operates the network behind it - useful for fraud analysis, traffic quality assessment, and abuse investigation. Use the IP lookup tool to find the ASN for any address.
Frequently Asked Questions
What is AS5400?
AS5400 is the autonomous system operated by British Telecommunications PLC, announcing 64 IPv4 ranges (713,472 addresses).
Who operates AS5400?
British Telecommunications PLC. An autonomous system is a network under a single administrative entity that exchanges routes with other networks via BGP.
How do I check if an IP belongs to AS5400?
Enter the IP into our free IP lookup - the result shows the ASN, operator, geolocation, and VPN/datacenter flags.