The default uPortal & CAS configuration is setup using localhost:8080 as the portal host-name and port. To switch hostnames there are several changes that need to be made. For the example below lets assume the configuration is changing from localhost:8080 to my.school.edu:80
uportal-impl/src/main/resources/properties/security.properties
There are two lines that need to be updated in security.properties
logoutRedirect.root=http://localhost:8080/cas/logout?url=http://localhost:8080/uPortal/Login
becomes
logoutRedirect.root=http://my.school.edu/cas/logout?url=http://my.school.edu/uPortal/Login
And
org.jasig.portal.channels.CLogin.CasLoginUrl=http://localhost:8080/cas/login?service=http://localhost:8080/uPortal/Login
becomes
org.jasig.portal.channels.CLogin.CasLoginUrl=http://my.school.edu/cas/login?service=http://my.school.edu/uPortal/Login