I am working on a database that stores Active Directory information. In order to make the columns, I need the maximum file size for active directory objects. This is what I found:

Active Directory Domain NetBIOS name (A.K.A. Pre-windows 2000 name): 15 characters
Active Directory Domain HOST name: 63 characters
Fully qualified domain name, or FQDN for objects except domain controllers: 63 characters per label, 255 characters total
Fully qualified domain name, or FQDN for domain controllers: 63 characters per label, 155 characters total
Site Name: 63 characters
OU Name: 64 characters
Common Name (CN): 64 characters
Distinguished Name (DN): 255 characters (You may be able to create a longer one, but you could experience authentication errors with LDAP binding)
Sam Account Name : 20 characters (256 in schema, but 20 character limit is for backward compatibility)
Computer Name: 15 characters
Display Name: 256 characters