從幾天前開始，上facebook總是斷斷續續到有反應。今晚終於忍受不住而又有半點空閒時間，便試試找找問題。
我使用的ISP是香港寬頻。
試了另一間ISP和Google的DNS來找尋facebook.com的IP地址，也是回傳以下結果。
facebook.com has address 66.220.158.11
facebook.com has address 69.171.224.37
facebook.com has address 69.171.229.11
facebook.com has address 69.171.242.11
facebook.com has address 66.220.149.11
facebook.com has IPv6 address 2a03:2880:2110:3f01:face:b00c::
facebook.com has IPv6 address 2a03:2880:10:1f02:face:b00c:0:25
facebook.com has IPv6 address 2a03:2880:10:8f01:face:b00c:0:25
facebook.com mail is handled by 10 smtpin.mx.facebook.com.
然後試過以上5個IPv4地址的port 80，竟然只有69.171.224.37的web server有反應，以下是telnet的測試方法。而其他4個只能connect，但發任何訊息也沒有反應。
$ telnet 69.171.224.37 80
Trying 69.171.224.37…
Connected to 69.171.224.37.
Escape character is ‘^]’.
asdasd
HTTP/1.0 400 Bad Request
Server: proxygen/129
content-type: text/plain
Date: Mon, 09 Jul 2012 15:35:24 GMT
Connection: close
Content-Length: 42
Error parsing message: invalid HTTP methodConnection closed by foreign host.
作為Linux桌面用戶，在/etc/hosts臨時加上以下一行，暫時解決問題，上facebook也變回暢順。
69.171.224.37 facebook.com www.facebook.com
真正問題的原因有代查明了。