Wildcard certificates are usually created with the wildcard listed as the Common Name (CN) of the Certificate Subject, such as the example in Figure 9-3. Cisco ISE release 1.2 supports this type of construction. However, not all endpoint supplicants support the wildcard character in the Certificate Subject.
All Microsoft native supplicants tested (including Windows Mobile) do not support wildcard character in the Certificate Subject.
You can use another supplicant, such as Cisco AnyConnect Network Access Manager (NAM) that might allow the use of wildcard character in the Subject field.
You can also use special wildcard certificates such as DigiCert's Wildcard Plus that is designed to work with incompatible devices by including specific subdomains in the Subject Alternative Name of the certificate.
Although the Microsoft supplicant limitation appears to be a deterrent to using wildcard certificates, there are alternative ways to create the wildcard certificate that allow it to work with all devices tested for secure access, including the Microsoft native supplicants.
To do this, instead of using the wildcard character in the Subject, you must use the wildcard character in the Subject Alterative Name (SAN) field instead. The SAN field maintains an extension designed for checking the domain name (DNS name). See RFCs 6125 and 2128 for more information.
For more information on Microsoft support of wildcard certificates, see: http://technet.microsoft.com/en-US/cc730460
http://www.cisco.com/c/en/us/td/docs/security/ise/1-2/user_guide/ise_user_guide/ise_man_cert.html#pgfId-1171626
https://supportforums.cisco.com/discussion/12245376/12511-unexpectedly-received-tls-alert-message-treating-rejection-client
