GTM - Alias -> Does the HTTP header change with Alias's?

Can you verify something for me. When creating alias within a Wide IP, if a client requests something like www.abc.com, and it’s a alias to instance-1.abc.com, will the HTTP header be modified to instance-1.abc.com instead of keeping the header www.abc.com? I know its easier to do each website with a WideIP, but my clients wants to do alias within a WideIP for mulitiple websites.

Request: www.abc.com

|-->WideIP: instance-1.abc.com

|----> Alias: www.abc.com

|----> Pool: instance-1.abc.com

|-----> Member: 9.9.9.9

Also, when creating the Alias's, I dont see any entries in ZoneRunner. Is that because the WideIP is managing the records instead of ZoneRunner?

RGW