Microsoft windows 2000 DNS manual Scavenging Algorithm, Configuring Scavenging Parameters

Page 33

the record at that time. The time at which records are scavenged depends on several server parameters.

Scavenging Algorithm

The server can be configured to perform scavenging automatically, using a fixed frequency. In addition, you can manually trigger scavenging on a server to perform immediate scavenging. When scavenging starts, the server attempts to scavenge all primary zones and succeeds if all the following conditions are met:

•The EnableScavenging parameter is set to 1 on the server.

•The EnableScavenging parameter is set to 1 on the zone.

•Dynamic update is enabled on the zone.

•The zone parameter ScavengingServers is not specified or contains the IP address of this server.

•The current time is greater than the value of the zone parameter StartScavenging.

The server sets StartScavenging whenever any of the following events occur:

•Dynamic update is turned on.

•EnableScavenging is set from 0 to 1 on the zone.

•The zone is loaded.

•The zone is resumed.

StartScavenging is equal to the time that one of the preceding events occurs plus the amount of time specified in the refresh interval for the zone. This prevents a problem that can occur if the client is unable to refresh records because the zone isn’t available—for example, if the zone is paused or the server is not working. If that happens and the server does not use StartScavenging, the server could scavenge the zone before the client has a chance to update the record.

When the server scavenges a zone, it examines all the records in the zone one by one. If the timestamp is not zero, and the current time is later than the time specified in the timestamp for the record plus the no-refresh and refresh intervals for the zone, it deletes the record. All other records are unaffected by the scavenging procedure.

Configuring Scavenging Parameters

This section discusses issues you must consider when configuring scavenging parameters.

To ensure that no records are deleted before the dynamic update client has time to refresh them, the refresh interval must be greater than the refresh period for each record subjected to scavenging within a zone. Many different services might refresh records at different intervals; for example, Netlogon refreshes records once an hour, cluster servers generally refresh records every 15 to 20 minutes, DHCP servers refresh records at renewal of IP address leases, and Windows 2000–based computers refresh their A and PTR resource records every 24 hours.

Windows 2000 White Paper

27

Page 32 Page 34
Image 33
Page 32 Page 34
Contents Windows 2000 DNS Microsoft Corporation. All rights reserved Contents Designing a DNS Namespace for the Active Directory Summary Page DNS Fundamentals Standards and Additional Reading Name Services in WindowsDraft-skwan-gss-tsig-04.txt GSS Algorithm for Tsig GSS-TSIG History of DNSHierarchy of DNS Domain Names Structure of DNSCom Edu Gov Mil Army Microsoft Int/net/orgMit Mydomain DNS and InternetDistributing the Database Zone Files and Delegation TTLMicrosoft My domain ftp Ntserver Replicating the DNS databaseQuerying the Database NEW Features of the Windows 2000 DNSName Server Resolver Root-server Gov Whitehouse.gov Time to Live for Resource Records Updating the DNS DatabaseActive Directory Storage and Replication Integration Active Directory Service Storage ModelWindows 2000 White Paper Controlling Access to Zones Replication ModelZone Type Conversions Protocol Description Incremental Zone TransferZone Log File Dynamic UpdateMaster DNS Server Slave DNS Server Ixfr and DS IntegrationDynamic Update of DNS Records Update AlgorithmDhcp Client Mixed EnvironmentSecure Dynamic Update Statically Configured ClientRAS Client Client ReregistrationEstablishing a security context by passing security tokens Secure Dynamic Update Policy Controlling Update Access to Zones and Names DnsUpdateProxy GroupAging and Scavenging DNS Admins GroupAging and Scavenging Parameters DefaultEnableScavenging Scavenging Period DescriptionRecord Life Span Scavenging Algorithm Configuring Scavenging ParametersInteroperability Considerations Unicode Character SupportDomain Locator Finish IP/DNS Compatible Locator DNS Record Registration and Resolver RequirementsLdap.tcp.dc.msdcs.DnsDomainName Kerberos.tcp.dc.msdcs.DnsDomainName IP/DNS DC Locator Algorithm Finish Discovering Site specific DCsCaching Resolver Fully-Qualified Query Name ResolutionUnqualified Single-Label Query Using Global Suffix Search OrderUnqualified Multi-Label Query Using Primary and Per-adapter Domain NamesUnqualified Single-Label Query Scenarios Name Resolution ScenariosMicrosoft Implementation of Negative Caching Fully-Qualified Query ScenariosDNS Server List Management Negative CachingAdministrative Tools WMI Support for DNS Server AdministrationDNS Manager Interoperability Issues Using Wins and Winsr RecordsUsing UTF-8 Characters Format DNS Server Performance Receiving Non-RFC Compliant DataUtilization Hardware components Sizing Server Capacity PlanningChoosing Names Internet Access ConsiderationsWindows 2000 White Paper Windows 2000 White Paper Windows 2000 White Paper VPN Com Yyy.com Zzz.com Windows 2000 White Paper Primary Zone YYY corporation ZZZ corporation VPN Firewall Computer Names Characters in NamesPer-Adapter Naming Full computer nameIntegrating ADS with Existing DNS Structure Domain name and sites. Active Directory domain name DNS Migration to Windows 2000 DNSPartitioning, and Replication Choosing your Zones Deploying DNS to Support Active DirectoryWins Referral Using Automatic ConfigurationIxfr Ixfr For More InformationWindows 2000 White Paper
Top Page Image Contents