53 - DNS
Enumeration
Grab version information
dig version.bind CHAOS TXT @<dns_host>
nmap --script dns-nsid -p 53 <dns_host>
Attempt a zone transfer
dig axfr @<dns_host>
dig axfr @<dns_host> <domain>
Grab all the extra info on a domain
dig ANY @<dns_host> <domain>