As of this build, Server Insiders get the choice of ISO format or VHDX format, with images pre-keyed, allieviating the need to enter a key during setup.
In 17035, Microsoft has reenabled Storage Spaces Direct (S2D) -- which it cut from Windows Server 1709, allegedly due to quality issues -- and added "some new and important updates to it," in Microsoft's words, including support for Data Deduplication. Also in this build, developers can use localhost or loopback to access services running in containers on the host.
Microsoft is making Project Honolulu Technical Preview 1711 Build 01003 available with this new test build. Honolulu is a graphical management tool for Windows Server. Within Honolulu, Microsoft is making updates and changes to Remote Desktop, Windows 10 client management, Switch Embedded Teaming and Data grid performance.
A new 17035 test build of the Redstone 4 Windows 10 client is likely to be available to testers tomorrow or later this week.
Don't forget: IT pros have options when it comes to feature updates to Windows Server. Those interested in getting new server features more quickly can opt for the Semi-Annual Channel (feature updates) which are supported for 18 months each and released twice a year. Windows Server 2016 is in the Long-Term Servicing Channel (LTSC) and will continue to be supported for 10 years with a new release out every two to three years.