python中的网络可用性测试脚本

Question

我一直在尝试编写脚本代码，以便自动ping一些98％的正常运行时间网络，如谷歌或Facebook等。虽然我尝试运行它时代码似乎很好但我在某些else上收到错误声明。

我认为我的if和elif有点搞砸了，所以有人可以伸出援助之手吗？

以下是代码：

import datetime
import os
import time 

now = datetime.time()
print ('Starting network availiability test at %s' % (now))
time.sleep(2) 
print ('The availiable servers for testing network availiabilty are: 1.Google 2.Apple 3.Facebook')
time.sleep(1)
host = raw_input('Please select which server should we ping in order to see if your network is up ?')
hostname1 = "google.com"
hostname2 = "apple.com"
hostname3 = "facebook.com"

if host == 1 :
print ('We are trying to reach Google, please wait')
resp = os.system('ping -n 1' + hostname1)

if resp == 0:
    print ('The server is reachable, so your network should be fine')
    else :
        print ('Google is not reachable. Your network seems down')

elif host == 2 :
print ('We are trying to reach Apple, please wait')
resp1 = os.system('ping -n 1' + hostname2)

if resp1 == 0:
    print ('The server is reachable, so your network should be fine')
    else :
        print ('Apple is not reachable. So your network seems down.')

elif host == 3 :
print ('We are trying to reach Facebook, please wait')
resp2 = os.system('ping -n 1' + hostname3)

if resp2 == 0:
    print ('The server is reachable, so your network should be fine')
    else :
        print ('Facebook is not reachable. Your network seems down.')