5 ms·

So, what should we ping for testing Internet connectivity ?

teddyh 8y ago
There’s ping.sunet.se as maintained by the Swedish University Network (i.e. the network connecting Swedish Universities; there is no single “Swedish University”).
- snazz 8y ago
  The advantage of pinging IPs is that you don’t have to have a working DNS setup to test your connection. If DNS does work, then your connection probably works, too.
  - 1_player 8y ago
    In this case one should run "ping -n", otherwise ping will hang trying to resolve the IP into an hostname, if the DNS is misbehaving or not responding.
    - sathackr 8y ago
      what default(included in OS) ping utility tries to reverse-lookup an address before pinging, and hangs if it can't. I've never observed this in any version of Windows nor Linux.
tinus_hn 8y ago
You are better off using traceroute to one of these addresses, you should at least get some route outside of your own network.
- bluejekyll 8y ago
  Traceroute uses ICMP as well, and may send more packets then ping. It works by setting the TTL on the ICMP packet, which is the number of route hops to traverse before the packet is dropped. Routers are supposed to ( this can be disabled, and is why you get * * * sometimes) respond with a TTL expired. So it starts with a TTL of 1, and then increments by 1 after each hop is discovered (or no response in some timeout).
  - detaro 8y ago
    On unixes, traceroute typically uses UDP by default (nowadays, ICMP is often an option, as are TCP SYN packets). Windows' tracert uses ICMP. I believe this is because you need root privileges/special capabilities to send ICMP packets.
    - bluejekyll 8y ago
      Yes. I wasn’t perfectly clear there. You’re correct for the initial src packet, the TTL exceeded response is ICMP, I think always.
  - tinus_hn 8y ago
    The important difference is that you can trust no host on the internet to actually respond to pings, especially not machines prone to receive DOS attacks, like public DNS resolvers. Traceroute is for testing connectivity, ping is an archaic test to see if a machine is running.
deleted 8y ago
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res0nat0r 8y ago
I just ping google.com when I need a quick sanity check.
- FreeFull 8y ago
  Which doesn't help if your DNS isn't working

There’s ping.sunet.se as maintained by the Swedish University Network (i.e. the network connecting Swedish Universities; there is no single “Swedish University”).

snazz 8y ago
The advantage of pinging IPs is that you don’t have to have a working DNS setup to test your connection. If DNS does work, then your connection probably works, too.
- 1_player 8y ago
  In this case one should run "ping -n", otherwise ping will hang trying to resolve the IP into an hostname, if the DNS is misbehaving or not responding.
  - sathackr 8y ago
    what default(included in OS) ping utility tries to reverse-lookup an address before pinging, and hangs if it can't. I've never observed this in any version of Windows nor Linux.

tinus_hn 8y ago

You are better off using traceroute to one of these addresses, you should at least get some route outside of your own network.

bluejekyll 8y ago
Traceroute uses ICMP as well, and may send more packets then ping. It works by setting the TTL on the ICMP packet, which is the number of route hops to traverse before the packet is dropped. Routers are supposed to ( this can be disabled, and is why you get * * * sometimes) respond with a TTL expired. So it starts with a TTL of 1, and then increments by 1 after each hop is discovered (or no response in some timeout).
- detaro 8y ago
  On unixes, traceroute typically uses UDP by default (nowadays, ICMP is often an option, as are TCP SYN packets). Windows' tracert uses ICMP. I believe this is because you need root privileges/special capabilities to send ICMP packets.
  - bluejekyll 8y ago
    Yes. I wasn’t perfectly clear there. You’re correct for the initial src packet, the TTL exceeded response is ICMP, I think always.
- tinus_hn 8y ago
  The important difference is that you can trust no host on the internet to actually respond to pings, especially not machines prone to receive DOS attacks, like public DNS resolvers. Traceroute is for testing connectivity, ping is an archaic test to see if a machine is running.

deleted 8y ago

[deleted]

res0nat0r 8y ago

I just ping google.com when I need a quick sanity check.

FreeFull 8y ago
Which doesn't help if your DNS isn't working