Command

openssl req -out fitcsecp.csr -new -newkey rsa:2048 -nodes -keyout fitcsecp_private_key.key -addext "subjectAltName = DNS:domain-name.com"

Fill out details

Country Name (2 letter code) [XX]:
State or Province Name (full name) []:
Locality Name (eg, city) [Default City]:
Organization Name (eg, company) [Default Company Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:
Email Address []:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

---

references:

1. How to create Certificate Signing Request with OpenSSL (ibm.com)