Web glossary
Not sure what an MX record, HSTS or TTFB is? We explain it briefly and in plain words, with examples and a way to check your own site right away.
DNS records
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A recordA record (DNS address record) -
AAAA recordAAAA record (DNS IPv6 record) -
CNAME recordCNAME record (DNS alias) -
MX recordMX record (mail exchanger) -
TXT recordTXT record (DNS text record) -
NS recordNS record (name server record) -
SOA recordSOA record (start of authority) -
CAA recordCAA record (CA authorization) -
PTR record (reverse DNS)PTR record (reverse DNS)
Security headers
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HSTS (Strict-Transport-Security)HSTS (Strict-Transport-Security) -
Content-Security-Policy (CSP)Content-Security-Policy (CSP) -
X-Frame-OptionsX-Frame-Options -
X-Content-Type-OptionsX-Content-Type-Options -
Referrer-PolicyReferrer-Policy -
Permissions-PolicyPermissions-Policy
Email: SPF, DKIM, DMARC
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SPFSPF record: what it is and how it works -
DKIMDKIM: the digital signature on your mail -
DMARCDMARC: the rule for mail that fails checks
SSL and HTTPS
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SSL certificateWhat is an SSL certificate -
TLSWhat is TLS -
HTTPSWhat is HTTPS -
wildcard certificateWhat is a wildcard certificate -
Let's EncryptWhat is Let's Encrypt -
certificate chainWhat is a certificate chain