I would say acme-challenge is one of the most used ones. How else would one get SSL certificates today

DNS TXT challenge for example. Also better because you can get wildcard certs.

Also, DNS-PERSIST-01 seems to be coming soon for Let's Encrypt, which should allow even people that can't easily dynamically update their DNS records to get wildcard certs. I assume this might become more widely used than HTTP-01 challenges.

	▲	inigyou 2 hours ago \| parent [-]
		I wish someone would write a blog post about the difference between DNS registrars and DNS hosts, because I've seen people assume they need to use a registrar that has an API in order to change their DNS records programmatically. I used to assume that too.