Unable to use DNS server name for User Source connection

Below error is shown if an existing LDAP connection is changed in ZCC to use DNS server name instead of IP address:
"...
Ensure that the address is valid and does not contain a port number.
..."

Workaround:
Keep using IP address or do not edit the connection, but create a new one instead.

API used to validate User Source server address only checks for valid IP address.