Wow. That's a great idea! nslookup is available on more devices than curl/wget.

Put it another way, if you cannot lookup dns, odds are curl won't work. Of course, some nets might require the use of internal dns servers and block outbound traffic to dns.

I always like to learn new trick. I'm definitely adding this nslookup trick to my IT swiss army knife kit. Thanks

With dig:

$ dig +short @resolver1.opendns.com myip.opendns.com