Resolve a DNS name to an IP and vice versa:
airvpn.org <--> 2001:41d0:a:6034:: Ping a host, if it pings you back, it's online and reachable:
$ ping airvpn.org -c4
PING airvpn.org(2001:41d0:a:6034:: (2001:41d0:a:6034::)) 56 data bytes
64 bytes from 2001:41d0:a:6034:: (2001:41d0:a:6034::): icmp_seq=1 ttl=56 time=19.4 ms
64 bytes from 2001:41d0:a:6034:: (2001:41d0:a:6034::): icmp_seq=2 ttl=56 time=17.9 ms
64 bytes from 2001:41d0:a:6034:: (2001:41d0:a:6034::): icmp_seq=3 ttl=56 time=18.6 ms
64 bytes from 2001:41d0:a:6034:: (2001:41d0:a:6034::): icmp_seq=4 ttl=56 time=18.9 ms
--- airvpn.org ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3006ms
rtt min/avg/max/mdev = 17.909/18.702/19.414/0.548 ms
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