You can use a a redirecting service to create a friendly URL for your end-users to use instead of the long EAS SAML URL. Redirecting services like https://redirection.io/ and https://www.easyredir.com/ are common options. Or you can search for similar redirecting services.
One thing to note is that a DNS cannot handle directing to paths (URL is https://auth.agilquest.com/eas-saml/saml/web/auth/SAMPLE, the path is /eas-saml/saml/web/auth/SAMPLE), but a redirecting service can.
We cannot use an IP because each Forum component sits behind at least 1 Load Balancer, and the load balancers determine where the traffic goes by the header information (the https:/auth.agilquest.com). Also, as of right now, Forum determines what it's going to do based on the path. A redirect service is the way to accomplish a friendly URL.