Common Name (required)

Your Exchange server's fully qualified domain name or the name of your Office communication server pool. If you are not sure what name to use, please refer to the notes below. To secure mail.example.com, your common name or one of your subject alternative names must be mail.example.com. Less commonly, you may also enter the IP address or short name of your internal server. For example, appserver1 or 192.168.1.200.

Subject Alternative

Subject Alternative Names (optional)

Comma separated.
Microsoft recommends including your Exchange server's NetBIOS name, its external and internal FQDN, and autodiscover.yourdomain.com.

For Office communications, server you need to put the name of servers in the pool, all your internal sip domain, and other needed FQDN.

Organisation:

Organization name

The exact legal name of your organization. Example: "UnifiedCommunications.eu." Less commonly, if you do not have a legal registered organization name, you must enter your own full name here.

Organizational unit / Departement:

Organizational unit / Departement: (optional)

Many people leave this field blank. This is the department within your organization which you want to appear in the certificate. It will be listed in the certificate's subject as Organizational Unit, or "ou." Common examples: Web Administration Web Security Marketing Engineering Information Technology

Town:

City

The city where your organization is legally located.

State:

State or Province

The state or province where your organization is legally located.

Country:

Country

The country where your organization is legally located.

Key Size

It's recommended to use 2048 bits. 1024 and 2048 bit keys are most common. Key sizes smaller than 1024 are considered insecure.