The command ping www.google.com might produce this output:
ping www.google.com
Pinging www.l.google.com [64.233.167.99] with 32 bytes of data:
Reply from 64.233.167.99: bytes=32 time=31ms TTL=239
Reply from 64.233.167.99: bytes=32 time=31ms TTL=239
Reply from 64.233.167.99: bytes=32 time=31ms TTL=239
Reply from 64.233.167.99: bytes=32 time=33ms TTL=239
Ping statistics for 64.233.167.99: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds: Minimum = 31ms, Maximum = 33ms, Average = 31ms
The first line of output confirms the command you issued Lets look at the first such output line:
bytes = 32 is the size of the ICMP Echo reply
time=... -- This is the time between the Echo Request and Reply. Since networks are dynamic, this time will probably be different for each reply received.
ttl=239 -- ``TTL'' means Time to Live. This is a counter in every IP packet. The sender (ping in this case) sets it to whatever it thinks a reasonable number is (the maximum is 255). Each router subtracts one, and packets get thrown out if TTL ever reaches 0. Assuming we started with TTL=255, this report gives us an estimate of the number of routers we passed through (16 in our example).
Source:
http://www.csis.ysu.edu/~gcperera/cclasses/3723/lab1.pdf
Reference:
http://en.kioskea.net/contents/outils-reseau/ping.php3
ping www.google.com
Pinging www.l.google.com [64.233.167.99] with 32 bytes of data:
Reply from 64.233.167.99: bytes=32 time=31ms TTL=239
Reply from 64.233.167.99: bytes=32 time=31ms TTL=239
Reply from 64.233.167.99: bytes=32 time=31ms TTL=239
Reply from 64.233.167.99: bytes=32 time=33ms TTL=239
Ping statistics for 64.233.167.99: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds: Minimum = 31ms, Maximum = 33ms, Average = 31ms
The first line of output confirms the command you issued Lets look at the first such output line:
bytes = 32 is the size of the ICMP Echo reply
time=... -- This is the time between the Echo Request and Reply. Since networks are dynamic, this time will probably be different for each reply received.
ttl=239 -- ``TTL'' means Time to Live. This is a counter in every IP packet. The sender (ping in this case) sets it to whatever it thinks a reasonable number is (the maximum is 255). Each router subtracts one, and packets get thrown out if TTL ever reaches 0. Assuming we started with TTL=255, this report gives us an estimate of the number of routers we passed through (16 in our example).
Source:
http://www.csis.ysu.edu/~gcperera/cclasses/3723/lab1.pdf
Reference:
http://en.kioskea.net/contents/outils-reseau/ping.php3
No comments:
Post a Comment