What Is DHCP Name Protection?
You
should protect the names that DHCP registers in DNS on behalf of other
computers or systems from being overwritten by other systems that use the same
names. In addition, you should also protect the names from being overwritten by
systems that use static addresses that conflict with DHCP-assigned addresses
when they use unsecure DNS, and when DHCP is not configured for conflict
detections
Name squatting is the
term used to describe the conflict that occurs when one client registers a name
with DNS but that name is already used by another client. This problem causes
the original machine to become inaccessible, and it typically occurs with
systems that have the same names as Windows operating systems.
What Is DHCP Failover?
DHCP
manages the distribution of IP addresses in TCP/IP networks of all sizes. When
this service fails, clients lose connectivity to the network and all of its
resources. A new feature in Windows Server 2012, DHCP failover, addresses this
issue.
DHCP
Failover
DHCP
clients renew their leases on their IP addresses at regular, configurable
intervals. When the DHCP service fails and the leases time out, the clients no
longer have IP addresses
The new DHCP
failover feature enables two DHCP servers to provide IP addresses and optional configurations
to the same subnets or scopes. Therefore, you can now configure two DHCP
servers to replicate lease information. If one of the servers fails, the other
server services the clients for the entire subnet.
Configuring DHCP Failover
To configure DHCP
failover, you need to establish a failover relationship between the two DHCP
servers’ services. You must also give this relationship a unique name
You can configure failover in one of the two
following modes
|
Mode
|
Characteristics
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Hot standby
|
In this mode, one server is the primary server and the
other is the secondary server. The primary server actively assigns IP
configurations for the scope or subnet. The secondary DHCP server only
assumes this role if the primary server becomes unavailable. A DHCP server
can simultaneously act as the primary for one scope or subnet, and be the
secondary for another.
The default MCLT value is five percent of the scope.
Hot Standby mode is best suited to deployments in which a
disaster recovery site is located at a different location. That way, the DHCP
server will not service clients unless there is a main server outage.
|
|
Load sharing
|
This is the default mode. In this mode both servers supply
IP configuration to clients simultaneously. The server that responds to IP
configuration requests depends on how the administrator configures the load
distribution ratio. The default ratio is 50:50.
|
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