The internet check is used to determine if the access point has a working internet connection. If the internet check is enabled, a gateway turns itself into a repeater, or a repeater will seek out a new gateway if its internet connection goes down. The internet check can be disabled under Configure -> Radio.
The internet check is run every 5 minutes. Each AP runs its own check. The preferred way of checking for internet availability is a UDP based traceroute to the following IP addresses in a random manner:
A UDP traceroute is used, as not all above IP addresses allow for a direct ping.
If any of the IP addresses are reached, the check is successful. However, if none of these IPs can be reached via traceroute, the node will try an HTTP based "ping" to all of the following URLs:
If any of the URLs are reached, the check is successful. If that also fails, the node will try to download a page from checkin.cloudtrax.com as a last resort.