CNAME filtering needs to be implemented

[endail]

Some DNS responses may actually be CNAMEs. These may point to non-Australian servers. For example:

$ dig _ntp._udp.federation.edu.au SRV

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25438
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;_ntp._udp.federation.edu.au.   IN      SRV

;; ANSWER SECTION:
_ntp._udp.federation.edu.au. 3600 IN    SRV     0 0 123 time.windows.com.