DNS For Client IP Configuration

In Active Directory network there many moving parts that need to be understood to help track down problems that may occur to the domain controllers, servers, and desktops. From the desktop troubleshooting, many things can be traced back to an IP address that is configured for IP DNS properties. If the IP address of the DNS is not correctly, many errors will occur, mostly behind the scenes and will not show you what the real problem is. In order to see what could go wrong, and to understand what is going on behind the scenes, this article will explain all the moving parts to flush common problems. When you finish reading, you will have a better understanding of how your desktop (and even the server) to obtain all the information they need to authenticate and access the network resources.

During boot, the operating system will do what it takes to get the core Windows files and parameters in place. This is done by the boot.ini, NTOSKRNL, and other files. All these files do is make sure that the last operating system and boot configuration put in place. This would include, Registry configuration file, and even down to ensure the correct operating system is selected, if there is some loaded on the computer.Once the operating system is ready, the computer need to configure the network. For most companies the network is configured to use DHCP, which stands for Dynamic Host Configuration Protocol. DHCP is very popular and most of you reading this already know that abbreviation. In order for you to contact the DHCP desktop it does broadcast network to contact the DHCP server. The DHCP server (s) have been listening to the request and will catch the broadcast request and respond when one of them heard the request.Note:Starting back in Windows 2000 if there is no DHCP server responds (meaning there is one in a network that does not respond or does not exist at all for the network), the desktop will automatically configure the IP address for itself. This is the APIPA address, which stands for Automatic Private IP Address. Range APIPA IP address 169.254.0.1 is to 169,254,255,254.When desktop communicate with the DHCP server, it will receive an IP configuration related. Configuring the DHCP server IP provides to its clients include:IP addressSubnet maskDefault GatewayDNS IP addressesWINS IP addressesDNS domain nameIf the desktop does not receive the correct IP settings, such as IP address or subnet mask, the desktop may not even communicate with other computers on the network. If the default gateway is the one given, then the desktop will not be able to communicate outside the subnet, which may not include a DNS server.If the desktop is configured to have the user be a local administrator, the user can also change the IP address manually. This will override the settings received by the DHCP server and in some cases can eliminate all communication with the DHCP server. In the end, the desktop can be restricted from communicating with all other computers on the network. It may also fail to communicate with the DNS server is correct, if not correct DNS server entries for the network and Active Directory domain where the desktop is.Now the desktop has all IP configuration information is important, it is now necessary to find and communicate with a domain controller for Active Directory domain. Instead of the initial communication is broadcast, as it was to communicate with the DHCP server, desktop directly communicate with the DNS server has been configured to locate a domain controller.Desktop makes direct contact with the DNS server and wait to hear back from the DNS server with information about the domain controller. When a DNS server receives a request from the desktop, it should analyze the information it receives.

• The DNS server will evaluate which subnet the active desktop, based on the IP address and subnet mask configured on the desktop

• The DNS server must evaluate which Active Directory site is located in the desktop, when a site is configured in DNS

• The DNS server must evaluate the sequence domain controller responds with, based on the priority domain controllers, sites, and the domain controller is configured to be used for other sites

The results that provide DNS server to the desktop called DCLIST, and is a hierarchical list of DNS domain controller based on criteria that were made during the analysis. The top DCLIST have a domain controller on the desktop site, then no other domain controllers in the site.Server DNS also provides other SRV (the service resource records) to the desktop, which is needed. This will include (for the Kerberos key distribution center) and KDC DFS server (if configured in DNS).If the desktop fails to obtain the SRV record will fail to use anything related to Active Directory, due to the fact that the only way the client can use the Active Directory is to acquire TCP, LDAP, DC, and KDC SRV records obtained from the DNS. This will make Kerberos fails, Group Policy failed, and all other communication to the domain controller through Kerberos and LDAP failed.Now the desktop has an IP address of a domain controller, it can make a direct connection to the first domain controller in the list. This should be a fast connection, a domain controller must be in the desktop site '.If the domain controller is available, it will respond and communicate with desktop and domain controllers. Desktop provides information to the domain controller so that the desktop can be confirmed as a member of a domain.Once the desktop is authentic, the desktop will receive important information designed to receive, such as startup scripts, Group Policy settings, etc. It is communicated from the domain controller via a secure connection, which split off from the domain controller via the NETLOGON share.There is a good chance will eventually authenticate desktop, but will use NTLMv2 or NTLM. Kerberos is only used when the desktop can obtain KDC and SRV records from DNS. Again, if there is no communication with the Kerberos domain controller, all functions of Active Directory failed to desktop.As you can see the DNS configuration for a desktop is very important. If there is an incorrect setting on the desktop, either manually or from a DHCP server, the desktop will not properly communicate with the DNS server or an Active Directory domain controller. With so much riding on the correct DNS configuration, it is important that DNS is configured correctly for all Windows computers are joined to an Active Directory domain. Without proper configuration, the desktop will not use Kerberos, Group Policy will not accept, and will not be able to use Active Directory correctly, due to the fact that no communication was made to the DNS server to accept the Active Directory SRV records placed there to find the source AD power.