Configuring Clients through DHCPv6
Exam: Microsoft 70-649 - TS: Upgrading Your MCSE on Windows Server 2003 to Windows Server 2008, Technology Specialist
When hosts are configured using DHCPv6 one can choose between a stateless or a stateful configuration. Host addresses in stateless configuration are not generate rather are autoconfigured. Host addresses are specified in stateful configuration.
In either of cases, the DNS Recursive Name Server DHCPv6 option (option 0023) can be used for assigning the IPv6 addresses. On choosing stateful configuration, configuration of IPv6addresses of DNS servers is done using the scope option. This means that different scopes can have different DNS servers. The server options for a scope are overridden by scope options. The method is preferred for configuration of DNS server IPv6 addresses that are not configured through the router discovery.
With a DHCPv6 configuration, parameters along with subnet prefixes can be received by an IPv6 host. One of the common uses to which DHCPv6 is put for IPv6 hosts that are Window based is for automatically configuring the IPv6 addresses of DNS servers.
When an IPv6 scope is configured in the current situation, 64 bit prefix needs to be specified. Allocation of host addresses from the complete 64 bit range for the prefix is done by DHCPv6 as a default setting. This allows specifying an exclusion range.
There are a number of DHCPv6 options that are available, the DNS server being the most important one. The other available options are dependent on compatibility issues pertaining to other systems like the UNIX NIS.
DHCPv6 and DHCPv4 are similar to a great extent. Examples supporting this point are overriding server options, DDHCPv6 requests and acknowledgments passing through the routers that are BOOTP-enabled and use of layer-3 switches for configuring clients on remote subnets. The 80:20 rule can be applied on both and server be configured in a manner that allows the subnet to contain 80% of the addresses that are available for the subnet and the remote subnet containing the remaining 20% of the addresses.
A DHCPv6 server on a remote subnet and is identically configured results in a failover. In case either server fails, the hosts on both the subnets continue to receive configuration.
Installing the DHCP Server Role on Server Core
The DHCP server role can be configured on Server Core by using the command start /w ocsetup DHCPServerCore. The technique proves particularly useful for networks that are complex. The DHCP server role can be configured and administered using netsh and net start commands.
The DHCP service is not capable of begining automatically on a Server Core. It can be done manually by using the net start DHCPServer command.
Using Hyper-V with DHCP
Software infrastructure and primary management tools are provided by Hyper-V. The tools can be used for creating and managing a virtual server computing environment in Windows Server 2008.
A virtual environment plays an instrumental role in reducing costs involved in operation and maintenance of physical servers, bringing down the amount of hardware along with developmental costs. The virtual environment has an advantage for it allows creating virtual clusters that go a long way in improving availability of server and providing foolproof coverage without using much of hardware.
One of the problems that may be encountered in the case of a virtual network is creation of a rogue DHCP server which may proceed to issue configurations in the cluster. In case a Hyper-V host is configured for using DHCP and the initial response is received from the rogue DHCP server, it may result in the Hyper-V host in being configured using an invalid DHCP lease.
DHCP in the Preboot Execution Environment
The Preboot Execution Environment (PXE) allows booting up the computers by using a network interface which is not dependent on the storage devices that are available or the operating system that is installed. Protocols like the DHCP and Trivial File Transfer Protocol (TFTP) are used. The firmware of the PXE client is extended using a set of already defined APIs. The firmware makes an attempt to locate a redirection service on the network for receiving information about PXE boot servers that are available. The firmware enquires the file path of a network bootstrap program (NBP) from the boot server. It proceeds to download the same into the RAM of the computer using a TFTP. It is optionally verified before it is executed. A PXE protocol is a combination of DHCP (used for locating the appropriate boot server/s) and TFTP (used for downloading the initial bootstrap program and associated files).
On initiating a PXE boot, the PXE ROM requests the DHCP server for an IP address during which the client computer is required to identify itself as being PXE-enabled. When the IP address is obtained an attempt to locate and establish connection with a PXE server for downloading NBP.
