Plesk allows you to configure its DNS server to provide the recursive service for queries. With recursive service allowed, your DNS server, when queried, performs all the lookup procedures required to find the destination IP address for the requester. When recursive service is not allowed, your DNS server performs minimal number of queries only to find a server that knows where the requested resource resides and to redirect the requester to that server. Therefore, recursive service consumes more server resources and makes your server susceptible to denial-of-service attacks, especially when the server is set to serve recursive queries from clients outside your network.
After your install Plesk, the built-in DNS server serves recursive queries only from your own server and from other servers located in your network. This is the optimal setting. If you upgraded from earlier versions of Plesk, your DNS server may be configured to serve recursive queries from any host.
If you want to change the settings for recursive domain name service: