One thing to remember. Carl Zeiss (Jena) and Zeiss Ikon aren't the same operation and can't be used interchangeably.
Zeiss Ikon did in fact hold the trademark to the Novar name. Although it never carries the name of the manufacturer, early versions of the Novar occasionally carry a serial number. I've never seen a Novar with a serial number on postwar cameras.
It's correct that the Novar was made by third-party lens makers, including Rodenstock, Steinheil and others.
Another fact: You'll never see the Novar on a camera other than a Zeiss Ikon, and if you do, it's not the original lens. And you'll never see a Rodenstock-branded lens on a Zeiss Ikon. Again, if you do, it's not the original lens.
Zeiss Ikon cameras were only allowed to use either a Novar or Carl Zeiss lenses with three exceptions:
1) Following the 1926 merger, you'll still see lenses from the predecessor companies, as it took a while to sort out production and the eventual product line.
2) After World War II and before Carl Zeiss had fully restarted lens production, Zeiss Ikon was permitted to use a Schneider-Kreuznach Xenar as its premium lens. I've seen Xenars on the Ikonta 35 and Super Ikonta A but not a Contax.
3) From what I can tell, just one lens survived the 1926 merger and World War II. It was the humble Goerz Frontar, which was used on nearly all Box Tengors (one Baby Box Tengor model uses a Novar) and a very cheap 1960s Instamatic.
Well, all that is enough to make your head spin.