Ping a host from the internet
Name a host or IP to send it 4 ICMP echo requests from hostnag's own probe and read the replies, the loss and the round-trip times. It runs once with a 10 second cap, the same runner a monitor uses; the result says where it ran.
How to read this
- Replies
- How many of the 4 packets came back, and the loss as a percentage. A monitor calls loss at or above its threshold degraded, never down.
- Round trip
- The fastest, average and slowest reply in milliseconds, and the jitter between consecutive replies.
- Pinged
- The address the name resolved to and whether it was reached over IPv4 or IPv6.
Questions
Is this a scan?
No. It sends 4 echo requests to the one address you name, the same as the ping command on your own machine, from a probe hostnag runs for this.
Why does it answer when my server is down, or stay silent when it is up?
Ping only says whether the network stack replies to ICMP. A host can answer pings with every service on it stopped, and many firewalls drop ICMP on purpose. Check the port or the URL for what people actually use.
Why is a private address refused?
A check from the internet can say nothing useful about a private or loopback address, and hostnag never dials into anyone's network on purpose.
Related
Read
Ping is not uptime monitoring: what an ICMP reply proves, and why a failure needs a second witnessAn ICMP reply proves a machine is there. A TCP connect on the right port is the first real test, and a failure needs a second place to confirm it.How to monitor an office internet link from both ends, so a filtered port and a dead line read differentlyReach the gateway from the internet and have a device inside check in, so a filtered port, a dead line and a new public address each read differently.
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