To have domain names appear in the 856 field of MARC records provided by OCLC WorldCat Cataloging Partner Records, you must use the institution level settings in Collection Manager to profile any/all domain names used by the provider. Domain names must be entered correctly and you may need to enter more than one domain name, though typically only one domain name is required. Leaving that field empty, having an error in the domain name, or a domain name that doesn't match to anything will cause any and all 856s to be retained (included) on the matching record that OCLC delivers.
First, under Knowledge Base Collection 856 Field>Add Subfields, choose "u" on the dropdown menu and in the Value field choose KB URL from the drop down menu. Next, add your domain name(s) to be retained in your MARC records.
To add or edit these domain names, in your WorldShare instance, access Collection Manager>Institution Settings>MARC Records>Customize Records>Knowledge Base Collection 856 Field>WorldCat 856 Field.
Under 'WorldCat 856 Field' option -> 'Retain fields with these domains', enter the domain(s) to be retained. Use the green circle with the white plus sign to add additional domain names and the red circle with the white minus sign to remove any unnecessary domain names.
Be sure to click the blue Save button near the top of the screen after making changes or your changes will not be retained.
If no domain name is entered, then all 856s in the matching item are delivered in the record so you could have a record with a lot of 856s you don't want.
Domain names must be entered correctly, without any typing errors. Incorrect domain names or domain names with typing errors will result in any/all 856s being retained in the MARC records OCLC delivers.
If your provider uses more than one domain name and it varies by record as to which domain is used, then all possible domains must be listed.
If the provider uses multiple domains in records but it includes every possible domain in every record, then just one of the possible domains must be listed.
If the provider only includes https://... domains in their records then that domain must be entered because if what is in this Collection Manager setting is only http://..., it will not match because that path is different than https:// (http vs https) and no domain will be provided in MARC records.
So if an 856$u contains https://doi.org/some/cars.html, then "http://doi.org" will NOT match, because of http vs https. Also, http://doi.org/other would not match because the path is different.