关于时间花费和TTL的问题

kaiying 2003-10-15 05:57:32

下面是我运行ping和tracert的结果:
218.78.248.219是当时上ADSL时动态分配的(与运行ping的电脑同连在一个HUB上)
C:\Documents and Settings\hl>tracert 218.78.248.219
Tracing route to 218.78.248.32 over a maximum of 30 hops

1 6 ms 10 ms 8 ms ip-Da-5200.online.sh.cn [218.1.27.50]
2 7 ms 6 ms 8 ms 218.78.248.219

Trace complete.
C:\Documents and Settings\hl>ping -t 218.78.248.219

Pinging 218.78.248.219 with 32 bytes of data:

Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 218.78.248.219:
Packets: Sent = 5, Received = 0, Lost = 5 (100% loss),
Control-C
C:\Documents and Settings\hl>ping -t -w 120000 218.78.248.219

Pinging 218.78.248.219 with 32 bytes of data:

Request timed out.
Reply from 218.78.248.219: bytes=32 time=2ms TTL=127
Reply from 218.78.248.219: bytes=32 time=2ms TTL=127
Reply from 218.78.248.219: bytes=32 time=1ms TTL=127
Reply from 218.78.248.219: bytes=32 time=3ms TTL=127

Ping statistics for 218.78.248.219:
Packets: Sent = 23, Received = 22, Lost = 1 (4% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 3ms, Average = 2ms
Control-C
^C
C:\Documents and Settings\hl>ping -t 218.78.248.219

Pinging 218.78.248.219 with 32 bytes of data:

Reply from 218.78.248.219: bytes=32 time=2ms TTL=127
Reply from 218.78.248.219: bytes=32 time=2ms TTL=127
Reply from 218.78.248.219: bytes=32 time=2ms TTL=127
Reply from 218.78.248.219: bytes=32 time=2ms TTL=127
C:\Documents and Settings\hl>ping -t 218.1.27.50

Pinging 218.1.27.50 with 32 bytes of data:

Reply from 218.1.27.50: bytes=32 time=9ms TTL=255
Reply from 218.1.27.50: bytes=32 time=10ms TTL=255
Reply from 218.1.27.50: bytes=32 time=9ms TTL=255

Ping statistics for 218.1.27.50:
Packets: Sent = 6, Received = 6, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 10ms, Average = 6ms
Control-C
有三个问题:
1. 218.1.27.50是到达的第一个路由器,为什么在ping中显示花费的时间比目的地 218.78.248.219还长呢(多次测试结果均如此)?
2. 第一次用默认的超时时间ping不通(TIMEOUT),后来将Timeout加大,就可以了,为什么以后再ping时,不加大TIMEOUT也可以呢?
3. 为什么只经过一个路由器TTL就由255减为127了呢?
问个很初级的问题:
C:\Documents and Settings\hl>tracert 218.78.248.219
Tracing route to 218.78.248.219 over a maximum of 30 hops

1 6 ms 10 ms 8 ms Da-5200.online.sh.cn [218.1.27.50]
2 7 ms 6 ms 8 ms 218.78.248.219

Trace complete.
反应时间为什么会有3个值啊

谢谢!

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