From HEXONET Wiki
Nameservers
Each Reseller has a set of nameserver hostnames assigned to their account by default and already pointing to the correct IP Addresses (ns1xxx.ispapi.net, ns2xxx.ispapi.net, ns3xxx.ispapi.net - where xxx is a numeric identifier associated with the backend server).
The following ip addresses are associated with our Anycast network, and can be used for setting up vanity nameservers:
NS1: 194.50.187.134 / 2a04:2b00:14cc::4 NS2: 194.0.182.1 / 2a04:2b00:14dd::4 NS3: 193.227.117.124 / 2a04:2b00:14ee::4