back by popular demand - a DNS calculator

Hi, all,

By popular request, I've restored the DNS calculator function as an
operational service. See:

http://www.isi.edu/touch/tools/dns-calc.html

(this was designed for a Sigcomm OO session, but it's been used several
places as an example why the DNS should NOT be anything more than a
mapping service)

Joe

PS - if you do happen to use it as an example, please do drop me a note;
I'd be very glad to track that info. and/or include a pointer to any
classes that use it.