Unit 1 Assignment 1 Windows 2008 Network Services
Unit 1 – Assignment 1 – Windows 2008 Network Services If you have a routed local area network and high-speed links that are fairly reliable, you might be able to use one DNS server for a larger, multiple sub-netted network area.If you have a high number of client nodes on a single subnet design, you might want to add more than one DNS server to the subnet to provide backup and failover if the preferred DNS server stops responding.
When determining the number of DNS servers you need to use, assess the effect of zone transfers and DNS query traffic on slower links in your network.Although DNS is designed to help reduce broadcast traffic between local subnets, it does create some traffic between servers and clients that should be reviewed, particularly when used in complexly routed LAN or WAN environments.
Consider the effects of zone transfer over slower speed links, like those typically used for a wide area network (WAN) connection.
Although the DNS Server service supports incremental zone transfers and DNS clients and servers can cache recently used names, traffic considerations are sometimes still an issue, particularly when DHCP leases are shortened and, as a result, dynamic updates in DNS are performed more frequently. One option for dealing with remote locations on WAN links is to set up a DNS server at these locations to provide caching-only DNS service. With most installations, you should have at least two server computers hosting each of your DNS zones for fault tolerance.
DNS was designed to have two servers for each zone, one as a primary server and the other as a backup or secondary server. When making any final determinations about the number of servers to use, first assess the level of fault tolerance you need for your network. Because there is no fixed limit to the maximum number of clients a DHCP server can service or to the number of scopes you can create on a DHCP server, the primary factors to consider when you determine the number of DHCP servers to use are network architecture and server hardware.
For example, in a single subnet environment, only one DHCP server is necessary, although you may want to use two servers or deploy a DHCP server cluster for increased fault tolerance. In multiple subnet environments, routers must forward DHCP messages between subnets, so router performance can affect your DHCP service. In both cases, DHCP server hardware affects service to clients.