Sunday, July 7, 2013

Application Partition for DNS

Application partitions for DNS
Application partitions are user defined partitions that have a custom replication scope. Domain controllers can be configured to host any application partition irrespective of their domains so long as they are in the same forest. This decouples the DNS data and its replication from the domain context. You can now configure AD to replicate only the DNS data between the domain controllers running the DNS service within a domain or forest.
 The other partitions are DomainDnsZones and ForestDnsZones. The system folder is the root level folder to store DNS data. The default partitions for Domain and Forest are created automatically.
 Aging and scavenging When the DNS records build up, some of the entries become stale when the clients have changed their names or have moved. These are difficult to maintain as the number of hosts increases. Therefore a process called  scavenging is introduced in the Microsoft DNS server that scans all the records in a zone and removes the records that have not been refreshed in a certain time period. when the clients register themselves with the dynamic DNS, their registrations are set to be renewed every 24 hours by default. Windows DNS will store this timestamp as an attribute of the DNS record and is used with scavenging.  Manual record entries have timestamps set to zero so they are excluded from scavenging.
"A "no-refresh interval" for the scavenging configuration option is used to limit the amount of unnecessary replication because it defines how often the DNS sever will accept the DNS registration refresh and update the DNS record.
 This is how often the DNS server will propagate a timestamp refresh from the client to the directory or file-system. Another option called the refresh interval specifies how long the DNS server must wait following a refresh for a record to be eligible for scavenging and this is typically seven days.

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