It receives queries from clients, performs the queries against other name servers, caches the results, and returns those results to the client.
A caching-only DNS server receives queries from clients, performs the queries against other name servers, caches the results, and returns those results to the client. It then returns subsequent queries for the specified host from the cache instead of submitting them to an external server. This reduces outgoing DNS traffic and speeds up name resolution.
You can configure the DNS service to work with forwarders either nonexclusively or exclusively. In nonexclusive mode, the DNS server checks its cache for the host. If the lookup fails, it forwards the query to the specified forwarder. If that query fails, the DNS server attempts to resolve the query on its own through the root servers.
For example, you must configure the DNS client settings to point to itself. During the DCPromo process, you must configure additional domain controllers to point to another domain controller that is running DNS in their domain and site, and that hosts the namespace of the domain in which the new domain controller is installed.
Do not configure the domain controller to utilize its own DNS service for name resolution until you have verified that both inbound and outbound Active Directory replication is functioning and up to date. ForestDnsName domain. After you have verified that replication has completed successfully, DNS may be configured on each Domain Controller in either of two ways, depending on the requirements of the environment.
The configuration options are:. Lengthy replication failures may result in an incomplete set of entries in the zone. This includes faster discovery of new or updated Domain Controller locator records, as replication lag time is not an issue. Provides a single authoritative DNS server, which may be useful when troubleshooting Active Directory replication issues.
This may result in apparent loss of connectivity, even to locations that are not across the lost network segment. While this strategy has many advantages, there are factors that should be considered before making this configuration change:. If this server fails to respond for any reason, the DNS client will switch to the server listed in the alternate DNS server entry. The ServerPriorityTimeLimit value is reached 15 minutes by default. For more information, click the following article number to view the article in the Microsoft Knowledge Base:.
Please note, only a failure to respond will cause the DNS client to switch Preferred DNS servers; receiving an authoritative but incorrect response does not cause the DNS client to try another server. As a result, configuring a Domain Controller with itself and another DNS server as Preferred and Alternate servers helps to ensure that a response is received, but it does not guarantee accuracy of that response.
DNS record update failures on either of the servers may result in an inconsistent name resolution experience. With these records, other domain controllers and computers can find Active Directory-related information. The domain controller must register its records with its own DNS server. If you do not configure forwarders, use the default root hints servers. For more information about how to remove the root zone, click the following article number to view the article in the Microsoft Knowledge Base:.
For example, you must configure the DNS client settings to point to itself. During the DCPromo process, you must configure additional domain controllers to point to another domain controller that is running DNS in their domain and site, and that hosts the namespace of the domain in which the new domain controller is installed.
Do not configure the domain controller to utilize its own DNS service for name resolution until you have verified that both inbound and outbound Active Directory replication is functioning and up to date. Failure to do so may result in DNS "Islands". For more information about a related topic, click the following article number to view the article in the Microsoft Knowledge Base:. ForestDnsName domain. After you've verified that replication has completed successfully, DNS may be configured on each Domain Controller in either of two ways, depending on the requirements of the environment.
The configuration options are:. While this strategy has many advantages, there are factors that should be considered before making this configuration change:. Only a failure to respond will cause the DNS client to switch Preferred DNS servers; receiving an authoritative but incorrect response does not cause the DNS client to try another server.
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