You may wonder if there is a limitation on how long a 'cn' (commonName) can be. Is there any max/upper limit on how many number of characters can be stored in 'cn' attribute?
Release : 14.1
Component : CA Directory
In general Directory does not put a limitation for the number of characters for cn (commonName).
But there are some limitation with the number character with DN (distinguishedName) for the Access Control and dxMemberURL.
1) When you enable Access Control, Directory limits the number of characters in the DN (distinguishedName) to about 391. See Directory Access Controls
2) The DXserver process (aka DSA) supports a maximum of 16334 characters for the dxMemberUrl attribute. See Configuring Dynamic Directory Roles