DNS Series 3: Comparison of forwarding function parameters forwarders first and forwarders only

The forwarding function after Bind8 can be used to create a cache within the scope of a large site on several servers to reduce the traffic of links to the external Domain Name Server. It can also be used to allow the server to query without directly accessing the internet, but to query external domain names. Forwarding occurs only when these servers are not authorized to query and there is no request record in the cache. Suppose there is an internal DNS2 HSZ (high security zone) internal host and external DNS1 network access in DMZ (non-military zone. You can use DNS2's forwarding function to query Internet hosts and dns1.
Keyword in the named. conf configuration file
Forward/Only
This parameter only indicates that if the forwarders list is not empty, the default value is first. The server first requests the forwarders list. If the DNS host in the forwarders list does not respond, the host will find the response by itself, if the value is set to only, the server will only request the DNS host in forwarders
Forwarders
The IP address used for forwarding. empty columns by default (no forwarding ). forwarding can also write the parameters of Global Forwarding in each domain. you can set different forwarders for some domains or have different forward only/first and no-forwarding behavior functions.
Example of parameters in named. conf

Options {directory "/var/named "; /** Using the DNS Server of the Network Provider as a forwarder * can make responses to queries faster and less of load on your * local network */forward first; forwarders {193.247.122.26 ;};};

Original article: http://laoxu.blog.51cto.com/4120547/1165687