DHCP Server for Windows » client

AllowDNSQuery

uwe — Sat, 06 Sep 2014 11:39:25 +0000

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.

Case	DEFAULTIPADDR	AllowDNSQuery	Requester	RESULT
1	SET	1	known	resolve IP
2	SET	1	unknown	DEFAULTIPADDR
3	SET	0	known	DEFAULTIPADDR
4	SET	0	unknown	DEFAULTIPADDR
5	NOT SET	1	known	resolve IP
6	NOT SET	1	unknown	resolve IP
7	NOT SET	0	known	resolve IP
8	NOT SET	0	unknown	resolve IP

WPAD

uwe — Mon, 01 Sep 2014 09:08:57 +0000

WPAD=http://server.domain/config.pac

Location of a proxy server (Web Proxy Auto Detection) used by Internet browsers to automatically detect proxy settings.

WINS

uwe — Mon, 01 Sep 2014 09:08:08 +0000

WINS_0=123.4.56.78
…
WINS_9=192.168.2.1

This entry sets the IP address of the WINS servers. You can setup up the 10 WINS servers using the entries WINS_0 to WINS_9.

SUBNETMASK

uwe — Mon, 01 Sep 2014 09:07:12 +0000

SUBNETMASK=255.255.255.0

The subnet mask is usually common to all clients and should be placed in the general section. This has to be the same as the subnet mask of the server machine that is setup in your network settings.

ROUTER

uwe — Mon, 01 Sep 2014 09:06:22 +0000

Specifying the Router / Gateway

ROUTER_0=123.4.56.78
…
ROUTER_9=192.168.2.1

This entry sets the IP address of the router or standard gateway. You can setup up to 10 routers by using the entries ROUTER_0 to ROUTER_9.

NODETYPE

uwe — Mon, 01 Sep 2014 09:05:18 +0000

NODETYPE=8  ; Default: 8

Default: 8, which means hybrid. I’ve never used something else than 8.

NEXTSERVER

uwe — Mon, 01 Sep 2014 09:04:18 +0000

IP address of the “next server”.

NEXTSERVER=123.45.6.7

This is typically used to specify a TFTP server in the BOOTP protocol.

NAME

uwe — Mon, 01 Sep 2014 09:02:44 +0000

“ClientPC” is send to the client as the hostname entry in the DHCP options.

NAME=ClientPC

This is supposed to be the name of the client machine. This entry doesn’t work with Windows clients, because they do not change the computer name.

LEASETIME

uwe — Mon, 01 Sep 2014 09:01:33 +0000

Lease time in seconds (decimal value).

LEASETIME=3600 ; 1 hour
Default: infinite

E.g. 86400 is the lease time for 1 day. Default is an infinite lease. The actual lease period for the clients IP address is the minimum of the configured LEASETIME and the lease duration the client is asking for.

LeaseEnd

uwe — Mon, 01 Sep 2014 09:00:17 +0000

LeaseEnd is specified as number of seconds since midnight (00:00:00), January 1, 1970 and defines the time at which this particular IP address expires.

LeaseEnd=1198953446

This entry is automatically created by the DHCP Server.
Lease times are important when a client requests an IP address and all addresses in the IP pool are already assigned to other clients. In that case the client whose lease time (LeaseEnd) has expired least recently is deleted from the INI file and the available IP address is used for the request.