Acme Evil

With a teacher research program and the use of SQL call, suddenly the network is interrupted. Ping DNS Server and Firewall do not get reply. The first reaction is: firewall was crash again! (Last week, an unknown crash) Go to the mainframe to reboot the firewall, but not solve the problem, watch the firewall log and found some session will suddenly coursing through and error. Suspect a client of LAN be got virus and cause the Internet paralysis; DNS Server reopened after it opened. But good times never often, is only for 1 minutes. Originally guess: "The catch virus PC users should not use the Internet, thus shutdown, the Internet has returned to good" Waiting for a 20 minutes still no improvement, at time has ping any servers with no replies. Why all of the servers? Even if the network traffic congestion, at least there will be the occasional one or two reply correct. Then suddenly to a telephone conversation, reminded "Maybe the switch hub that connect all the servers was crashing?" It's right, all reopened were get after switch hub reboot. However, why switch hub crash for no reason at all?
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下午正與某位老師研究SQL的使用以及程式的呼叫，突然網路都斷線了。Ping DNS和防火牆卻得不到Reply回應，第一個反應就是：防火牆又掛了！(上星期才不明的掛了一次) 到了主機房再重開防火牆，沒有解決問題，進防火牆看日誌檔，發現某些session會突然飆高且error，懷疑是區域網路中有一台Client中毒了，而造成網路癱瘓；重開DNS Server之後卻通了。只是，好景不常，只通了一分多鐘。本來猜測："中毒的PC使用者應該是覺得網路不能使用了，因而關機，所以網路又恢復順暢，等他在關機就好了。"等了一、二十分鐘還沒有改善，這時候已經Ping不到任何一台Server了，為什麼會Ping不到全部的Server呢？就算網路塞車，至少也會有偶爾的一、二個reply才對。這時突然來了一通電話，提醒了"會不會是串接所有主機的Switch Hub掛掉了？" 果然，重開Switch Hub一切就恢復正常了。可是，為什麼無緣無故Switch Hub會掛掉呢？