I configured my DNS as:

; Name servers
cryptodistributed.org.    IN    NS    ns1.cryptodistributed.org.
cryptodistributed.org.    IN    NS    ns2.cryptodistributed.org.
seed.cryptodistributed.org.  IN  NS  seedvps.cryptodistributed.org.

; A records for name servers
ns1    IN    A    104.131.55.112
ns2    IN    A    104.131.18.252
seedvps    IN    A    104.131.20.192

And chainparams.cpp as I originally had it configured;

vSeeds.push_back(CDNSSeedData("cryptodistributed.org", "seed.cryptodistributed.org"));

but I am now getting the following error;

connect() to 228.18.131.104:9751 failed: Network in unreachable (101)
Cannot connect to kjy2eqzk4zwi5zd3.onion:9751: unsupported network

104.131.18.228 is the IP address of my seednode as is configured as follows;

unsigned int pnSeed[] =
{
      0x688312e4
};

So I'm not sure why it's attempting to connect to that IP instead.

There are no visible attempts from the coin daemon to connect to the DNS seeder on 104.131.20.192.

On the VPS 104.131.20.192, on which I'm running the dns seeder using;

./dnsseed -h seed.cryptodistributed.org -n 104.131.20.192

I get;

$ 0/1 available (1 tried in 800s, 0 new, 0 active), 0 banned; 10 DNS requests, 14 db queries