NCSI has been around for a long time now.
It can be disabled by using the policy at Computer Configuration\Computer Configuration\Administrative Templates\System\Internet Communication Management \ Turn off Windows Network Connectivity Status active tests
however, disabling it has impacts on technologies such as direct access.
Recently a client was getting prompted for auth form their proxy, for all connections, wired, wireless and 4G.
Msftncsi.com had been added as un-authenticated location for proxy access, but it was still occurring on Windows 10 1809.
Googling this found a few sites talking about proxy issues, disabling NCSI or re-directing this. I did not want to disable or re-direct, and the proxy issues didnt seem to fit our situation.
I ended up going down the wireshark path and discovered that www.msftconnecttest.com is now the DNS name used for NCSI resolution.
Added this to the list of sites which do no required auth – and all is good with the world again.