[judge2020]

Unless you want to pay for the business plan with a CNAME Setup[0], you do need to use their DNS offering, even if the rest of your site's DNS records are 'unproxied'. If you just want to try tunnels at all, with a non-descript hostname, Tunnel gives out subdomains that end in trycloudflare.com[1].

If you're referring to the TOS issue that is often discussed here, it depends on what that subdomain is, since Cloudflare doesn't just want to be pushing binary data for free. If the subdomain is some website that is primarily used in the browser, CF will generally be fine leaving it up even if you push TBs a day, but if it's just a file host CF has been known to flag that for abuse and disable proxying for the domain[2]. As for why they bother with a free plan with such cryptic rules, their S1 explains it[3].

0: https://support.cloudflare.com/hc/en-us/articles/36002034883...

1: https://developers.cloudflare.com/cloudflare-one/connections...

2: https://community.cloudflare.com/t/the-way-you-handle-bandwi...

3: https://l.judge.sh/85EH

(I am not a CF employee nor your lawyer)