Hi esotericizm, thanks for the suggestion.
As far as I can tell the DNS appears to be properly configured;

$ nslookup seed.cryptodistributed.org

Server:     8.8.8.8
Address:   8.8.8.8:53

Non-authoritative answer:
Name:  seed.cryptodistributed.org
Address:  104.131.53.44

however when I run:

dig -t NS seed.cryptodistributed.org

;;Question Section:
;seed.cryptodistributed.org.   IN     NS

;;AUTHORITY SECTION
cryptodistributed.org.   IN   SOA   dns5.doteasy.com hostmaster.doteast.com

I contacted my hosting provider but they said it looks correct.
Re-reading https://bitcointalk.org/index.php?topic=599623.0 I'm now wondering if I should have created an NS record like so;

NS Record:
seed.cryptodistributed.org     104.131.53.44

Rather than;

cryptodistributed.org        seed.cryptodistributed.org