Time to live (TTL) is a mechanism that limits the lifespan of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or timespan has elapsed, data is discarded. In computer networking, TTL prevents a data packet from circulating indefinitely. In computing applications, TTL is used to improve performance of caching or improve privacy.
TTL is a timer value included in packets sent over TCP/IP-based networks that tells the recipients how long to hold or use the packet or any of its included data before expiring and discarding the packet or data.
Time-to-Live (TTL) has been renamed renamed in IP version 6. The field is called the hop limit and has the same function as the TTL field in IPv4.
The ping, traceroute, and the pathping network utilities both make use of the TTL value to attempt to reach a given host computer or to trace a route to that host.
The default Windows 95/98 TTL value is 32 hops. Folloing are the list of Devices / Operating system with Default TTL values
OS/Device Version Protocol TTL
AIX
TCP 60
AIX
UDP 30
AIX 3.2, 4.1 ICMP 255
BSDI BSD/OS 3.1 and 4.0 ICMP 255
Compa Tru64 v5.0 ICMP 64
Cisco
ICMP 254
DEC Pathworks V5 TCP and UDP 30
Foundry
ICMP 64
FreeBSD 2.1R TCP and UDP 64
FreeBSD 3.4, 4.0 ICMP 255
FreeBSD 5 ICMP 64
HP-UX 9.0x TCP and UDP 30
HP-UX 10.01 TCP and UDP 64
HP-UX 10.2 ICMP 255
HP-UX 11 ICMP 255
HP-UX 11 TCP 64
Irix 5.3 TCP and UDP 60
Irix 6.x TCP and UDP 60
Irix 6.5.3, 6.5.8 ICMP 255
juniper
ICMP 64
MPE/IX (HP)
ICMP 200
Linux 2.0.x kernel ICMP 64
Linux 2.2.14 kernel ICMP 255
Linux 2.4 kernel ICMP 255
Linux Red Hat 9 ICMP and TCP 64
MacOS/MacTCP 2.0.x TCP and UDP 60
MacOS/MacTCP X (10.5.6) ICMP/TCP/UDP 64
NetBSD
ICMP 255
Netgear FVG318
ICMP and UDP 64
OpenBSD 2.6 & 2.7 ICMP 255
OpenVMS 07.01.2002 ICMP 255
OS/2 TCP/IP 3.0
64
OSF/1 V3.2A TCP 60
OSF/1 V3.2A UDP 30
Solaris 2.5.1, 2.6, 2.7, 2.8 ICMP 255
Solaris 2.8 TCP 64
Stratus TCP_OS ICMP 255
Stratus TCP_OS (14.2-) TCP and UDP 30
Stratus TCP_OS (14.3+) TCP and UDP 64
Stratus STCP ICMP/TCP/UDP 60
SunOS 4.1.3/4.1.4 TCP and UDP 60
SunOS 5.7 ICMP and TCP 255
Ultrix V4.1/V4.2A TCP 60
Ultrix V4.1/V4.2A UDP 30
Ultrix V4.2 – 4.5 ICMP 255
VMS/Multinet
TCP and UDP 64
VMS/TCPware
TCP 60
VMS/TCPware
UDP 64
VMS/Wollongong 1.1.1.1 TCP 128
VMS/Wollongong 1.1.1.1 UDP 30
VMS/UCX
TCP and UDP 128
Windows for Workgroups TCP and UDP 32
Windows 95 TCP and UDP 32
Windows 98 ICMP 32
Windows 98, 98 SE ICMP 128
Windows 98 TCP 128
source : catatanteknisi.com
