Incidentally, for this DNS have custom-built records SRV. Theese records for Kerberos, for example:


$ dig _kerberos._tcp.host.com srv

;; QUESTION SECTION:
;_kerberos._tcp.host.com.   IN   SRV

;; ANSWER SECTION:
_kerberos._tcp.host.com. 3550 IN   SRV   10 10 88 kerberos.host.com.


Requesting for any DNS-name SRV-record in this format, you can find the address of Kerberos-server for this domain. Similarly, we can do for Bitcoin by queryng about: "_bitcoin._tcp.host.com" or something.

All this is done covertly, human sees only the right part of the name: host.com

And for domain names with sub-domains Kerberos using TXT records to enable the customer to understand what realm it belongs to:


$ dig _kerberos.grid.host.com txt

;; QUESTION SECTION:
;_kerberos.grid.host.com.   IN   TXT

;; ANSWER SECTION:
_kerberos.grid.host.com. 3587 IN   TXT   "HOST.COM"


Bitcoin can use this for subdomains like www:

_bitcoin.www.host.com. 3587 IN   TXT   "HOST.COM"

i.e., human can send bitcoin to www.host.com, bitcoin client check TXT _bitcoin.www.host.com for DNS-name of bitcoin "realm", than check SRV _bitcoin._tcp.host.com and, finally, sends bitcoins to IP, specified by this SRV-record.

This scheme is really a part of Kerberos standart and used, I think, more than 15 years.