AllowDNSQuery goes along with the built-in DNS functionality. A client who performs DNS queries that is not known to the DHCP Server (not in the ini file) can get a default IP address returned regardless of the name it wants to resolve. This is a security feature that limits the DNS function to known clients. Since V1.9.3 AllowDNSQuery defines this behavior on a per client basis. If AllowDNSQuery is set to 1 then the client can resolve names to IP addresses with DNS queries. If AllowDNSQuery is set to 0 then whatever is configured as DEFAULTIPADDR is returned for every name.

Please assume the following INI file:

[General]
...
AllowDNSQuery=0
...

[DNS-Settings]
EnableDNS=1
DEFAULTIPADDR=192.168.0.1

[00-00-00-00-00-01]
IPADDR=192.168.0.10
Hostname=Computer_1

[00-00-00-00-00-02]
IPADDR=192.168.0.11
Hostname=Computer_2
AllowDNSQuery=1

In this example, only Computer_2 will be able to resolve DNS queries to the real IP addresses. Computer_1 will observe that regardless of the name he wants to resolve, he will always get 192.168.0.1 in return.

The influence of AllowDNSQuery to the behavior is such that, whenever DEFAULTIPADDR is set, the DEFAULTIPADDR is returned when the requester is unknown (not listed in the INI file) or AllowDNSQuery is 0.