Plug-Ins Overview

Simple DNS Plus v. 5.1
Copyright © 1999-2008 JH Software ApS

Simple DNS Plus has a plug-in system for providing additional/optional functionality. This allows us (and 3rd parties) to develop new features without cluttering the base product, and allowing users to select which of these features they want - or don't want.


Simple DNS Plus supports 3 types of plug-ins:

"Get Host" plugs-ins are designed to fetch a single host record - that is the IP address (IPv4/IPv6) for a host name - and optionally the reverse.
"Get Answer" plugs-ins are designed to fetch multiple DNS records of any type.
NOTE: "Get Answer" plug-ins only work with the "unlimited zones" license type.
"Skip" plug-ins do not fetch or provide DNS records directly, but make it possible to skip a number of following plug-in instances when the plug-in's conditions are met. This works like a script statement "IF <condition> THEN GOTO X" providing powerful flow control to the plug-in instances list.


The standard Simple DNS Plus installation comes with the following 6 "Get Host" plug-ins:

DHCP Server plug-in
A basic DHCP server which provides IPv4 addresses and settings to local computers and devices. The DHCP data is also used to serve DNS requests (forward and reverse) making it very simple to locate any local DHCP client by name on a local network.
For details see KB1216.
Domain Blacklist plug-in
Redirects requests for domain names on a blacklist. Can be used to block banner ads, malicious web-sites, porn web-sites, etc. Doing this at a central DNS server makes it easy to enforce company/family policy for your entire network. You can direct browser requests for listed entries either to a dummy IP address, or to an IP address of your own web-server where you serve up some type of  "not allowed" message.
For details see KB1253.
Hosts File plug-in
Serves host (A / AAAA) and reverse (PTR) DNS records from a standard hosts file.
For details see KB1210.
MS SQL Server plug-in
Queries a Microsoft SQL Server for host records and optionally reverse records.
For details see KB1211.
Regular Expressions plug-in
Use Regular Expressions to pair host domain names to IP addresses. More powerful and flexible than simple wildcard records.
For details see KB1212.
Weighted Round Robin plug-in
Serves IP addresses (A / AAAA records)  for a host name round robin from a weighted list.
IP addresses are rotated so that the first visitor gets one IP address, the next visitor another IP address, etc. However IP addresses with higher weight values are served more often than IP addresses with lower weight values. This makes it possible for example to send more traffic to high capacity servers in a round robin set.
For details see KB1252.


A single "Get Answer" plug-in:

MS SQL Server Plus plug-in
Queries a Microsoft SQL Server for one or more DNS records of any type.
For details see KB1249.


And two "Skip" plug-ins:

Domain Whitelist plug-in
Used to prevent Simple DNS Plus from querying other plug-in instances about specified domain names.
Typically this is used in combination with blacklist plug-ins, but it works with all plug-in types and might also be used for more advanced "flow control".
For details see KB1254.
Scheduler plug-in
Used to control when (during what time periods) Simple DNS Plus will query other plug-in instances or not. Can be used to temporarily suspend/enable other plug-ins that are only needed/wanted at specific times. For example to skip blacklists during lunch breaks and non-working hours.
For details see KB1257.


Additional plug-ins are available for download from


Plug-ins are instantiated in the Options dialog / DNS / Plug-Ins section.


Some plug-ins (including the DHCP Server plug-in) have their own View - a dockable sub-window in the main window.

The plug-in architecture is open for users and 3rd parties interested in developing their own plug-ins.
In short, this is all based on the .NET Framework 2.0 interfaces "IGetHostPlugIn", "IGetAnswerPlugIn" and "ISkipPlugIn" found in the "sdnsplugin.dll" file supplied with Simple DNS Plus. More information about developing plug-ins is available on-line in KB1238.