dig — DNS Information Groper
# Basic lookup
dig example.com
# Short output
dig +short example.com
# Specific record type
dig example.com MX
dig example.com TXT
dig example.com NS
dig example.com AAAA
# Query specific DNS server
dig @1.1.1.1 example.com
dig @8.8.8.8 example.com
# Trace the resolution path
dig +trace example.com
# Reverse lookup
dig -x 198.48.63.241
# Show TTL remaining
dig example.com | grep -A1 "ANSWER SECTION"
nslookup
# Basic lookup
nslookup example.com
# Specific record type
nslookup -type=MX example.com
nslookup -type=TXT example.com
# Query specific server
nslookup example.com 1.1.1.1
Common Diagnostic Scenarios
Check Propagation
# Compare results from multiple DNS servers
dig +short example.com @1.1.1.1 # Cloudflare
dig +short example.com @8.8.8.8 # Google
dig +short example.com @9.9.9.9 # Quad9
Verify Email DNS
dig example.com MX +short
dig example.com TXT +short | grep spf
dig mail._domainkey.example.com TXT +short
dig _dmarc.example.com TXT +short
Check Nameservers
dig example.com NS +short
Install dig
# Ubuntu/Debian
sudo apt install -y dnsutils
# Rocky/Alma
sudo dnf install -y bind-utils