Which type of file is created from issued intermediate, root, and primary certificates for SSL installation on a server?

DER (Distinguished Encoding Rules) is a binary encoding format for certificates, which, while valid, is less common than PEM for bundling multiple certificates for server installations and is not a text-based format.

A CSR (Certificate Signing Request) is a request submitted to a Certificate Authority to obtain a certificate; it is not the actual issued certificate or a bundle of certificates for installation.

PEM (Privacy-Enhanced Mail) is a widely used file format for X.509 certificates that can contain a single certificate or a chain of certificates, including primary, intermediate, and root certificates, making it suitable for SSL server installations. PEM files are text-based, using Base64 encoding.

CRT is a common file extension for certificate files, but it refers to the content (a certificate) rather than the specific format that allows bundling multiple certificates like PEM. A .crt file could be either PEM or DER encoded.