For Enterprise SSL certificate, You will be receiving the following three files from comodo:
Intermediate CA UTNAddTrustServerCA.crt
domain/site certificate yourdomainname.crt
Or you can download root and intermediate CA files from here.
Go to Key Manager.
Install the new IIS SSL Server certificate by clicking on the key in the www directory (usually a broken key icon with a line through it), and select 'Install Key Certificate'.
Enter the Password.
you are prompted for bindings, add the IP and Port Number. 'Any
assigned' is acceptable if you do not have any other IIS SSL
certificates installed on the web server.
Note: Multiple certificates installed on the same web server will require a separate IP Address for each because SSL does not support host headers.
Go to the Computers menu and select the option 'Commit Changes', or close Key Manager and select 'Yes' when prompted to commit changes.
The new IIS SSL Server certificate is now successfully installed.
Back up the Key in Key Manager by clicking on Key menu> Export ->
Backup File. Store the backup file on the hard drive AND off the server.
Step 2: Installing the Root & Intermediate Certificates:
IIS SSL Certificate will have been emailed to you. The email will
also contain two other Certificates: the
ROOT certificate and
CA certificate .Save
these Certificates to the desktop of the web server machine.
It is essential that you have installed these two Certificates on the machine running IIS 4. You may also download them from the support section of the website:
Once you have installed the Certificates, restart the machine running IIS 4. You must now complete one of the following procedures - the procedure you follow is dependent on the Service Pack that has been implemented on your machine running IIS4.
Install the above certificates in your Internet Explorer by opening each certificate and clicking 'Install Certificate'. You may then use this IIS CA batch file to transfer all root certificates from your Internet Explorer to the IIS (see Microsoft Knowledge Base Q216339).
Service Pack 4:
Install the above certificates manually in a specific root store (you may also want to read (see Microsoft Knowledge Base Q194788):
Install the Root certificate by double clicking on the corresponding file this will start an installation wizard
select Place all certificates in the following store and click browse
select Show physical stores
select Trusted Root Certification Authorities
select Local Computer, click OK
back in the wizard, click Next, click Finish
Repeat the same for the UTNAddTrustServerCA.crt however choose to place the certificates in the Intermediate Certification Authorities store.
Same as SP4.
Same as SP5.
Reboot the web server to complete the installation.