Internal URL, do i always have to add the port?

Internal URL, do i always have to add the port?

i am setting up AD Manager using an internal CA cert for ssl.  when i set it up it defaulted to using 8443.  i tried to change it to 443 but it told me 443 was in use.  when i netstat, it shows that 443 is in use by the same process as 8443, which is AD Manager.
is it possible to use a naked URL without the port at the end?  i just want to have the techs go to https://ADMP.domain.com   instead of going to https://ADMP.domain.com:8443.