I am the designated DNS Directorate reviewer for draft-ietf-dnsop-zoneversion.
This is the third review I am doing - in my last review on the -08 version I 
came to the conclusion that the document is ready for publication. 

The draft is going to be published as Informational RFC. The document is well 
written and defines an EDNS option which can be used for debugging purposes.

There were only a few minor changes on making the document more clear and 
readable compared to the -08 version from my last review. In addition 
several references were added.

Overall I think the document is ready for publication.