Windows 2003 dns block sites

Dynamic updates are sent or refreshed periodically. By default, computers send an update every twenty-four hours. If the update causes no changes to zone data, the zone remains at its current version, and no changes are written. Updates that cause actual zone changes or increased zone transfers occur only if names or addresses actually change. Names are not removed from DNS zones if they become inactive or if they are not updated within the update interval of twenty-four hours. DNS does not use a mechanism to release or to tombstone names, although DNS clients do try to delete or to update old name records when a new name or address change is applied.

This value determines how long other DNS servers and clients cache a computer's records when they are included in a query response. Scope clients can use the DNS dynamic update protocol to update their host name-to-address mapping information whenever changes occur to their DHCP-assigned address.

This mapping information is stored in zones on the DNS server. This enables the client to notify the DHCP server as to the service level it requires. In this case, the option is processed and interpreted by Windows Server-based DHCP servers to determine how the server initiates updates on behalf of the client. This is the default configuration for Windows. To configure the DHCP server to register client information according to the client's request, follow these steps:.

By default, updates are always performed for newly installed Windows Server-based DHCP servers and any new scopes that you create for them. The following examples show how this process varies in different cases. For these DHCP clients, updates are typically handled in the following manner:. After you integrate a zone, you can use the access control list ACL editing features that are available in the DNS snap-in to add or to remove users or groups from the ACL for a specific zone or for a resource record.

For more information, search for the "To modify security for a resource record" topic or the "To modify security for a directory integrated zone" topic in Windows Server Help. By default, dynamic update security for Windows Server DNS servers and clients is handled in the following manner:. Windows Server-based DNS clients try to use nonsecure dynamic updates first. If the nonsecure update is refused, clients try to use a secure update.

Also, clients use a default update policy that lets them to try to overwrite a previously registered resource record, unless they are specifically blocked by update security. By default, when you use standard zone storage, the DNS Server service does not enable dynamic updates on its zones. For zones that are either directory-integrated or use standard file-based storage, you can change the zone to enable all dynamic updates.

This enables all updates to be accepted by passing the use of secure updates. The secure dynamic updates functionality can be compromised if the following conditions are true:. For more information, see the "Security considerations when you use the DnsUpdateProxy group" section. The secure dynamic update functionality is supported only for Active Directory-integrated zones.

If you configure a different zone type, change the zone type, and then integrate the zone before you secure it for DNS updates. If you use secure dynamic updates in this configuration with Windows Server-based DNS servers, resource records may become stale.

In some circumstances, this scenario may cause problems. For example, if DHCP1 fails and a second backup DHCP server comes online, the backup server cannot update the client name because the server is not the owner of the name. In another example, assume that the DHCP server performs dynamic updates for legacy clients. If you upgrade those clients to a version supporting dynamic updates, the upgraded client cannot take ownership or update its DNS records.

To solve this problem, a built-in security group named DnsUpdateProxy is provided. If all DHCP servers are added to the DnsUpdateProxy group, the records of one server can be updated by another server if the first server fails. Also, all the objects that are created by the members of the DnsUpdateProxy group are not secured.

Therefore, the first user who is not a member of the DnsUpdateProxy group and that modifies the set of records that is associated with a DNS name becomes its owner.

When legacy clients are upgraded, they can take ownership of their name records at the DNS server. If every DHCP server that registers resource records for legacy clients is a member of the DnsUpdateProxy group, many problems are eliminated.

If you are using multiple DHCP servers for fault tolerance and secure dynamic updates, add each server to the DnsUpdateProxy global security group. Also, objects that are created by the members of the DnsUpdateProxy group are not secure. Therefore, you cannot use this group effectively in an Active Directory-integrated zone that enables only secure dynamic updates unless you take additional steps to enable records that are created by members of the group to be secured. Covered by US Patent.

Come for the solution, stay for everything else. Welcome to our community! I heard I could create HOST A records and block it that way but don't have any clue on how to do that and what I have tried hasn't worked. I do my own DNS hosting and all my servers point to just one so I know there has to be a way to do it. Please help, got students looking at all kinds of crap. Chris Dent. Most Points The Distinguished Expert awards are presented to the top veteran and rookie experts to earn the most points in the top 50 topics.

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I want to block website like youtube,ibibo for my client computer in dns server of win how do i do that?? Pls help. Share Flag. All Answers.