PING之後
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Pinging qa.usernet.com.tw [210.201.75.113] with 32 bytes of data:

Reply from 192.168.255.6: TTL expired in transit.
Reply from 192.168.255.6: TTL expired in transit.
Reply from 192.168.255.6: TTL expired in transit.
Reply from 192.168.255.6: TTL expired in transit.

Ping statistics for 210.201.75.113:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tracert之後
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tracing route to qa.usernet.com.tw [210.201.75.113]
over a maximum of 30 hops:

1 54 ms 55 ms 69 ms 172.16.95.8
2 55 ms 69 ms 55 ms clnbg2-1.seed.net.tw [139.175.95.1]
3 68 ms 55 ms 55 ms R58-10.seed.net.tw [139.175.58.10]
4 55 ms 55 ms 68 ms R56-233.seed.net.tw [139.175.56.233]
5 55 ms 69 ms 69 ms 192.72.97.202
6 69 ms 68 ms 55 ms 192.168.255.21
7 55 ms 69 ms 68 ms 192.168.255.6
8 69 ms 68 ms 69 ms 192.168.255.6
9 69 ms 68 ms 69 ms 192.168.255.6
10 55 ms 69 ms 68 ms 192.168.255.6
11 69 ms 55 ms 69 ms 192.168.255.6
12 69 ms 54 ms 69 ms 192.168.255.6
13 55 ms 69 ms 68 ms 192.168.255.6
14 69 ms 55 ms 69 ms 192.168.255.6
15 68 ms 55 ms 69 ms 192.168.255.6
16 55 ms 68 ms 69 ms 192.168.255.6
17 55 ms 69 ms 68 ms 192.168.255.6
18 69 ms 55 ms 69 ms 192.168.255.6
19 69 ms 55 ms 69 ms 192.168.255.6
20 69 ms 69 ms 68 ms 192.168.255.6
21 55 ms 69 ms 68 ms 192.168.255.6
22 55 ms 68 ms 69 ms 192.168.255.6
23 68 ms 69 ms 69 ms 192.168.255.6
24 54 ms 69 ms 55 ms 192.168.255.6
25 68 ms 69 ms 69 ms 192.168.255.6
26 69 ms 68 ms 69 ms 192.168.255.6
27 69 ms 68 ms 69 ms 192.168.255.6
28 69 ms 55 ms 68 ms 192.168.255.6
29 69 ms 69 ms 68 ms 192.168.255.6
30 69 ms 55 ms 69 ms 192.168.255.6

Trace complete.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
這是怎麼一回事ㄚ,怎麼tra到最後一直都是192.168.255.6ㄚ,這代表什麼呢? 還有TTL expired in transit.是什麼意思ㄚ? 為什麼會這樣ㄚ,麻煩你們了
謝謝你們!!

如果封包一直卡在某幾台路由器，表示他們的路由表有問題了。
ttl講簡單一點就是當ip在網路上傳送的時候，用來告訴主機這個封包的保存時間。每次經過一台router則ttl就會減去1，最後會歸零。當收到封包的路由器的ttl已經到達零的時候就會將封包丟棄，並且使用icmp往回傳time to live exceeded訊息。這樣的機制用來確保不會產生無窮迴圈。