DNS & Glossary

BGP prefix

The CIDR block of IP addresses a network announces to the world via BGP — the routing unit that determines the path traffic takes to reach an address.

What it is

Networks advertise reachability for blocks of addresses — prefixes like 93.184.216.0/24 — using BGP. Routers across the internet learn which ASN can reach each prefix and choose paths accordingly. RPKI cryptographically validates that an AS is authorised to announce a prefix, guarding against hijacks.

Why it matters

  • Prefixes and their origin ASNs determine how traffic is routed and where it can be intercepted.
  • RPKI validation of a prefix helps detect and prevent BGP hijacking.

Common mistakes

  • Ignoring RPKI status, which leaves routing vulnerable to prefix hijacks.

How WebInspect checks this

  • The Network Inspector reports the BGP prefix and RPKI/route-origin details for an IP.