TTL (Time To Live)

Time To Live is a header field that limits how long a packet or record persists. In IP, TTL is decremented at each router hop and the packet discarded at zero, preventing routing loops and enabling traceroute. In DNS, TTL is the validity period of a cached record. TTL values are also useful as security and fingerprinting signals.

Categories: Internet and Routing

TTL in context

Telecom networks depend on Internet-style routing (BGP, DNS, MPLS) for interconnect. Route hijacks and DNS abuse can degrade or intercept signaling, which is why RPKI and DNSSEC are now standard hardening for carrier networks.

To place TTL in the wider telecom-security picture, review 3G, 3GPP, A5/1, A5/2, A5/3 and ASN — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

3G
3GPP
A5/1
A5/2
A5/3
ASN
Authorization
BGP

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.