Hi,

I have found a typo in nsupdate help. Nsupdate manual page states
nxrrset means no such rrset must exist, yxrrset vice versa.

But if you run nsupdate and type help, you get this:
...
[prereq] nxdomain name    (does this name not exist)
[prereq] yxdomain name    (does this name exist)
[prereq] nxrrset ....     (does this RRset exist)
[prereq] yxrrset ....     (does this RRset not exist)
...

I have attached simple patch for swapping them.
Petr Menšík