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Registration & WHOIS
Registrar, registration and expiry dates
Nameservers
Where DNS is managed
IP Address (A Record)
Where the domain points
Mail (MX Records)
Where email for this domain is delivered
SPF Record
Authorised senders — prevents email spoofing
DMARC Record
Email authentication policy
DKIM Record
Email signing key — checked at common selectors
Other TXT Records
Verification tokens and other text records