Many of our servers whitelist ports to harden themselves against attacks, and this whitelisting may not be done on the server itself (e.g. some of our servers d

Many of our servers whitelist ports to harden themselves against attacks, and this whitelisting may not be done on the server itself (e.g. some of our servers do it on upstream networking equipment). We would also have to run some sort of HTTPd on ALL the servers in each round-robin being verified, which would essentially mean all our servers. DNS-01 is a much better fit for us (and our DNS server software makes it somewhat less painful).