問(wèn)題
    Which command can verify Application Layer connectivity between 2 hosts?
    A. arp
    B. ping
    C. telnet
    D traceroute
    E. plp
    題目意思：以下命令當(dāng)中那個(gè)是在應(yīng)用層驗(yàn)證兩個(gè)主機(jī)的聯(lián)通性的命令？
    Telnet tests the Application layer, ping test the Network layer.Telnet is an application used to remotely configure a device. If telnet is succesfful you know that full 7 layer stack on the sending and receiving host are configured correctly and are in working order
    因?yàn)閠elnet命令是工作在應(yīng)用層，ping命令是工作在網(wǎng)絡(luò)層的，telnet是應(yīng)用于遠(yuǎn)程控制設(shè)備的，所以如果能telnet成功的話(huà)，這就證明了兩臺(tái)主機(jī)或設(shè)備已經(jīng)聯(lián)通了，在聯(lián)通性上面已經(jīng)沒(méi)有問(wèn)題了。
    該題目主要考學(xué)員命令工作的層面，和OSI七層的關(guān)系。
    正確答案：C