We pick j.root-servers.net, one of the 13 root servers (1), and ask it about autonomica.org and learn that org is delegated to six name servers (2), so we ask a2.org.afilias-nst.info where we learn that autonomica.org is delegated to three name servers, including slave.sth.netnod.se (3), so we ask that one and get the following answer:
The three name servers slave.gbg.netnod.se, slave.sth.netnod.se and slave.svl.netnod.se together
Five of the about thirty domains that use name server group 1 use only the mail server mail.netnod.se. Worth noting is that five of the domains that only use the mail server mail.netnod.se use name server group 1.
The two name servers slave.gbg.netnod.se and slave.sth.netnod.se together
Five of the seven domains that use name server group 2 use only the mail server mail.netnod.se. Worth noting is that five of the domains that only use the mail server mail.netnod.se use name server group 2.
The mail server mail.netnod.se only
There are 15 domains that only use the mail server mail.netnod.se.
Five of those use name server group 1. Worth noting is that five of the domains that use name server group 1 use only the mail server mail.netnod.se.
Five of them use name server group 2. Worth noting is that five of the domains that use name server group 2 use only the mail server mail.netnod.se.