TTL
Abbreviation with 3 meanings
| Stands for | Time to live |
|---|---|
| Meanings | 3 |
| Categories | Technology & Computing, Science & Engineering, Business & Finance |
TTL has three meanings. The most common are Time to live (networking) and Transistor-transistor logic (electronics & electrical); it can also stand for Through the line.
Meanings of TTL at a glance
| # | TTL stands for | Context |
|---|---|---|
| 1 | Time to live | Technology & Computing › Networking |
| 2 | Transistor-transistor logic | Science & Engineering › Electronics & Electrical |
| 3 | Through the line | Business & Finance › Marketing & Advertising |
1. Time to live
Technology & Computing · Networking Abbreviations
In IP, an 8-bit counter in each packet that every router decrements by one, so packets caught in a loop are discarded when it reaches zero. In DNS, the TTL is the number of seconds resolvers may cache a record before asking the authoritative server again.
Example: Drop the DNS TTL to 300 seconds a day before migrating the site to the new host.
The IP field was originally meant to count seconds, but in practice it became a hop count, and IPv6 renamed it Hop Limit. Traceroute works by sending packets with TTL 1, 2, 3 and so on and recording which router reports each expiry. Caches and CDNs use the same idea for how long content stays fresh. In electronics, TTL means transistor-transistor logic, an unrelated meaning.
2. Transistor-transistor logic
Science & Engineering · Electronics & Electrical Abbreviations
Family of digital logic chips built from bipolar transistors, running on 5 volts, that dominated electronics from the late 1960s into the 1980s. The 7400 series, from simple gates to counters, became a universal standard, and "TTL levels" still describe 5-volt logic signals.
Example: The vintage arcade board is built from dozens of 7400-series TTL chips.
James Buie invented TTL at TRW in 1961, and Texas Instruments' 7400 series made it an industry staple. A TTL input reads below 0.8 V as low and above 2.0 V as high. CMOS logic has replaced TTL in most designs, but "TTL serial" often refers to logic-level UART signals. In photography TTL means through-the-lens metering.
3. Through the line
Business & Finance · Marketing & Advertising Abbreviations
Campaign approach that blends mass-media (ATL) and targeted (BTL) activity into one integrated plan, for example a TV ad driving viewers to an in-store promotion and social contest.
Example: The agency pitched a TTL campaign linking the TV spot to a QR code giveaway.
The term arose as digital media made the old above-and-below line split less meaningful.
Related abbreviations
More networking abbreviations
- STUN – Session Traversal Utilities for NAT
- TCP – Transmission Control Protocol
- TCP/IP – Transmission Control Protocol/Internet Protocol
- TFTP – Trivial File Transfer Protocol
- UDP – User Datagram Protocol
- UPnP – Universal Plug and Play
- UTP – Unshielded twisted pair
- VLAN – Virtual LAN
See all 113 networking abbreviations →