Which protocol is commonly used to transmit X.509 certificates?

Question

Options

• AHTTPS
• BFTPS
• CSMTPS
• DLDAP

• B
  4% (1)
• C
  4% (1)
• D
  93% (26)

Explanation

LDAP (Lightweight Directory Access Protocol) is designed to query and retrieve entries from directory services, which commonly store X.509 certificates as attributes of user or device objects - making it the standard protocol for publishing and distributing certificates in PKI environments. HTTPS, FTPS, and SMTPS all use X.509 certificates internally during their TLS handshakes to authenticate and encrypt connections, but they are consumers of certificates, not mechanisms for transmitting them to other parties. The key distinction is that LDAP treats the certificate itself as data to be looked up and retrieved, whereas the other three protocols treat it as an authentication credential used behind the scenes.

Memory tip: Think "LDAP = Lookup Directory And Pull" - when a system needs to find and fetch a certificate (e.g., from Active Directory), it speaks LDAP. If a protocol is just securing a channel with TLS, it's using a certificate, not transmitting one.

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