The default gateway on host A is incorrectly configured.
it specifies the remaining " life" of the packet
Time-to-Live (TTL) is a value in an Internet Protocol (IP) packet that tells a network router whether or not the packet has been in the network too long and should be discarded.
The TTL (Time To Live) value is a number associated with network routing packets. An information packet will only be forwarded to a certain number of routers before the packet is dropped (deleted). The TTL is a counter decreased by 1 when the packet is forwarded to another router. When the TTL reaches zero, it will not be forwarded to another router.
TTL is a value in data packet of Internet Protocol. It communicates to the network router whether or not the packet should be in the network for too long or discarded. Usually, data packets might not be transmitted to their intended destination within a stipulated period of time. The TTL value is set by a system default value which is an 8-bit binary digit field in the header of the packet. The purpose of TTL is, it would specify certain time limit in seconds, for transmitting the packet header. When the time is exhausted, the packet would be discarded. Each router receives the subtracts count, when the packet is discarded, and when it becomes zero, the router detects the discarded packets and sends a message, Internet Control Message Protocol message back to the originating host.
nothing
It's a time-to-live field designating that the packet is OK to forward from one device to another for a certain amount of time. If the packet gets caught in a routing loop, it won't just go back and forth forever. If that were allowed to happen, many other packets would be doing the same thing, just being mis-routed back and forth between the confused devices, until the available bandwidth on the link was saturated. The TTL assures that the packet will not be forwarded by the very next routing device that reads the packet's TTL field and sees that its TTL has expired. The packet would be discarded at that point.
TTL- Time To Live
the ttl compatability is nothing but the time to live factor of a packet in the dns system
Time -to-live
See time-to-live (TTL) packet
The TTL or Time To Live is a value used to make packets eventually die, so they don't end up in infinite loops, clogging the network over time. Certain network devices decrement this value (routers mainly) by one as they process it. When the TTL reaches zero, the packet is discarded. Each Operating System implements its TCP/IP stack differently and starts packets off with the TTL of their choosing (the default TTL of the stack can be changed, but rarely is). Windows is 128 Linux is 64 Cisco is 256 So if your TTL is around 128 (remember the TTL gets decremented by certain devices) you are PROBABLY pinging a windows box. If it's near 256, probably Cisco etc. You can't rely on this information because other network devices can rewrite the TTL in a packet, but it's a decent indication of the OS on the other end, especially if it's a box you own and you aren't going through firewalls etc.
SCIENCE