Subtitles of the Movie

This module deals with integrating DHCP with dynamic DNS or DDNS. DDNS is pretty much essential in most modern networks and especially important with a network that uses DHCP. Why? Well we'll talk about more in the next module but DNS works to resolve computer names into IP addresses. Well the very nature of DHCP is that those IP addresses will change from day to day and sometimes within the same day IP addresses will change on client computers. So how do you make sure that the name to IP address mappings remain consistent and accurate. You do it with dynamic DNS. Well all this is really setup by default by Server 2003 anyway. So you don't really have to worry about this too much, but what I want to point out is that DHCP can be configured or is configured, to update both the 'A' and pointer records of the host records and the pointer record for DHCP clients in DNS, or just the 'A' record or the host record for clients depending on which operating system is being updated. Now again we'll talk more about the host records and the pointer records but this is the forward lookup mapping, this is the reverse lookup mapping. Again this will be fleshed out in full detail in the next chapter. To set this up or to just view where these options are setup from, look at the properties of the server, this also you can set on the properties of the scope and from the DNS tab is where these options are setup. So enable DNS dynamic updates according to the settings below, this is turned on by default, dynamically update DNS A and pointer records if requested by the DHCP client, or you can always no matter what, update DNS A and pointer records. This is the default, notice also the default on a client machine running Server 2003 or XP or Windows 2000. Properties, TCP/IP properties, advanced DNS, they automatically try to register the connections address in DNS. So they already try, those operating system try to update their records. Now let me show you what this behavior is and here it is, here is the default behavior for a client running operating system 2000, XP or Server 2003. DHCP client goes out and request an IP address. The lease is acknowledged and then the client updates the DNS server with the record for the host name, the DHCP server then updates with the reverse lookup record. With operating systems prior to Window 2000 it's handled a little differently, the DHCP server does all of the work and I'll show you what this looks like. So this is what it would look like for an earlier version of Windows that do not support dynamic DNS updates. The DHCP client, say this is a Windows 98 machine, requests an IP address, is sent an IP address and then the DHCP server on that client's behalf, registers both the 'A' record, the forward lookup record and the reverse or pointer lookup record. So this is the behavior, this is where it's configured from and again you can specify, maybe you don't want to have the entire server behave that way. You can do this on the scope level as well by setting up a DNS server. Which DNS server will be contacted by the way? The one that is configured for the DHCP server through the properties of TCP/IP or in the clients case if the client's updating DNS then it will be the DHCP server that they are handed with some of their scope options. So any client of this scope if we've configured it this way will contact that DNS server and update it's 'A' record.