The IP address for that FTP (and now HTTP) server changed so infrequently over the years, on the order of decades, that in the past IANA/ICANN published advance notice to the public before changing it. (A non-DNS way of changing an IP address.) It is probably hardcoded into lots of DNS software as this address is where root.hints is served. This is how ICANN DNS is boostrapped. From a single IP address. There are a few IP addresses I have memorised, 198.41.0.4, 192.5.6.30 and this one. Yes, I still use FTP to fetch the root.zone.

In the days of ye olde internet it used to be called "ftp.internic.net". Today, I believe it is still "internicftp.vip.icann.org".

To make curl work

   curl -k https://192.0.32.9 

or

   curl https://www.internic.net/domain/root.zone

I use curl in examples on HN because so many paople love it but TBH it is not a program I use myself. I use custom programs I wrote for doing HTTP requests. Finer controls than curl.