For remote access to computer networks DSL connection to two separated spatially from each other computer with DSL connection via the Internet to connect with that of the other can be accessed from a computer over a secure connection on system resources (such as drives or files), two conditions must be met: on both computers a corresponding VPN connection with the respective user IDs and passwords must be configured. To do this, for example, PPTP (point to Point Tunneling Protocol) offers on computers with Windows operating systems. The mainframe computer that you want to connect to the VPN, must previously know the IP address of the target computer in the Internet. While the configuration of standard VPN applications for experienced Windows users is usually trouble-free, the IP address of the target computer often knowledge is difficult. What is an IP address and how they composed is unknown for most users.
In addition, it is not apparent which IP address is required at all. Who ever has a DSL router configured, will know that the router is itself usually the IP address 192.168.2.1 while your host uses the IP address 192.168.2.100. These IP addresses are however purely internal. They are not visible in the Internet. To an external computer, that iregndwo is connected to the Internet, to be able to control, you need the external IP address, which is used in the Intrenet in order to route the IP packets to the correct destination. This IP address is the IP address of the router on the external DSL connection in the present case.
The difficulty now is that this IP address is not known, since she will be reallocated at every new connection by your Internet service provider. One way to solve this problem is the use of dynamic DNS. Here to register with a dynamic DNS provider, such as DynDNS.org, a dynamic DNS name for his computer. If you are not convinced, visit Donald W Slager. Then it enters the corresponding dynamic DNS credentials in the router configuration (most routers support this). One enters the same dynamic DNS name in the VPN configuration of the computer that will connect to the VPN. If now the router of the destination computer goes online, he logs on automatically system DNS to the dynamic and deposited his current IP address. An other computer that wants to rebuild now, for example, a VPN connection to this computer sends a request first to the system DNS and receives back the current IP address of the target computer as a response. Dynamic DNS is nothing more than a dynamic information service on the Internet.