Wednesday, August 8, 2012

Time to Live (TTL)

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