
As a rule of thumb, make sure to backup registry before making any changes. These values are stored in the following Registry container: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters. Active Directory Maximum Limits – Scalability How to set MaxFieldLength and MaxRequestBytes values? Starting with Windows Server 2012, the default value of the MaxTokenSize registry entry is 48,000 bytes. However, because of HTTP’s base64 encoding of authentication context tokens, we do not recommend that you set the maxTokenSize registry entry to a value larger than 48,000 bytes. If you are using Kerberos for IPSEC key management, the limit of 65,536 bytes.

The maximum allowed value of MaxTokenSize is 65,535 bytes.
