Is it possible to register DNS servers in NSI Registry database?

Yes, it's possible for gTLD and non-Russian ccTLD domain names. DNS servers shall not be mandatory registered at the domain names delegation in .RU and .SU TLDs.

To add child DNS servers for the gTLD and non-Russian ccTLD domain names it shall be necessary to go to R01 client area, open "GTLD and non-Russian ccTLD domain names" section and select "Child DNS servers management" option in "Actions" column in the line with your domain name.