Check CAA records before issuing certs dig
Show which CAs may issue certs; missing CAA lets any CA issue
dig +short CAA example.com
more dig
all 11 commands →
Resolve SRV records for service discovery
dig +short SRV _sip._tcp.example.com
Force TCP and show remaining TTL
dig +tcp +ttlunits +noall +answer example.com @8.8.8.8
Clean answer-only output
dig +noall +answer example.com
Find authoritative nameservers via NS chase
dig +nssearch example.com
Attempt a zone transfer (AXFR)
dig axfr @ns1.example.com example.com