In
a typical DNS query event, a client computer attempts to resolve a FQDN to an
IP address.
which
include features such as:
• Forwarding
• Conditional forwarding
• Stub zones
•
Net mask ordering
Forwarding
A forwarder
is a network DNS server that you configure to forward DNS queries for host
names that it cannot resolve to other DNS servers for resolution.
Conditional
Forwarding
You
also can use conditional forwarders to forward queries according to specific
domain names.
Stub
Zones
A stub zone is a
copy of a zone that contains only those resource records necessary to identify
that zone’s DNS servers.
A stub zone consists
of the following:
•
The delegated zone’s start of authority (SOA) resource record, name server (NS)
resource records, and host (A) resource records
• The IP address of one or more
master servers that you can use to update the stub zone
Conditional Forwarding vs.
Stub Zones
Conditional forwarder and stub
zones perform similar functions. The distinguishing difference between
conditional forwarders and stub zones are that conditional forwarders work
better across firewalls, while stub zones are more dynamic when DNS-servers are
added and removed. If you have firewalls, you usually configure two DNS servers
that can be accessed by a partner behind the firewall; therefore, you need to
configure conditional forwarding. For internal DNS servers, where you usually
do not have firewalls or permit DNS traffic to all DNS servers behind the
firewall, you can use stub zones that automatically learn about new DNS
servers.
Net mask Ordering
There are various reasons for
having multiple IP addresses associated with a single name, for example, load
balancing a web page. Net mask ordering returns addresses for type A address
records (A record) DNS queries that prioritize resources on the client computer’s
local subnet to the client. In other words, addresses of hosts that are on the
same subnet as the requesting client will have a higher priority in the DNS
response to the client computer.
Localization
is based on IP addresses. For example, if there are multiple A records that are
associated with the same DNS name, and each of the A records are located on a
different IP subnet, net mask ordering returns an A record that is on the same
IP subnet as the client computer that made the request.
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