Optimizing DNS Name Resolution

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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