Set resetforwarders using dnscmd

To add IP addresses to a dns server as forearders, do the following.
1. Assume the dns server to which to add forwarders is "dnsserver", forwarder ip address is 192.168.1.100
2. Run the command below to reset forwarders
dnscmd dnsserver /resetforwarders 192.168.1.100
To Set the timeout period (say 20 secs) the DNS server waits for a response from the forwarder, run

dnscmd dnsserver /resetforwarders 192.168.1.100 /Timeout 20
Also to prevent the DNS server from performing its own iterative queries if the forwarder fails to resolve a query, run
dnscmd dnsserver /resetforwarders 192.168.1.100 /slave
To allow iterative queries, run
dnscmd dnsserver /resetforwarders 192.168.1.100 /noslave