DNS ISSUE

Below is an excerpt from Microsoft:

If the client requests to register its resource records with DNS, the client is responsible for generating the dynamic UPDATE request per Request for Comments (RFC) 2136. Then, the DHCP server registers its PTR (pointer) record.

Assume that this option is issued by a qualified DHCP client, such as a DHCP-enabled computer that is running Windows Server 2003, Microsoft Windows 2000, or Microsoft Windows XP. In this case, the option is processed and interpreted by Windows Server 2003-based DHCP servers to determine how the server initiates updates on behalf of the client.

For example, you can use any one of the following configurations to process client requests: • The DHCP server registers and updates client information with its configured DNS servers according to the client request.

This is the default configuration for Windows Server 2003-based DHCP servers and clients that are running Windows Server 2003, Windows 2000, or Windows XP. In this mode, any one of these Windows DHCP clients can specify the way that the DHCP server updates its host A and PTR resource records. If it is possible, the DHCP server handles the client request for handling updates to its name and IP address information in DNS.

To configure the DHCP server to register client information according to the client's request, follow these steps:1. Open the DHCP properties for the server or the individual scope.
2. Click the DNS tab, click Properties, and then click to select the Dynamically update DNS A and PTR records only if requested by the DHCP clients check box.
 
• The DHCP server always registers and updates client information with its configured DNS servers.

This is a modified configuration supported for Windows Server 2003-based DHCP servers and clients that are running Windows Server 2003, Windows 2000, or Windows XP. In this mode, the DHCP server always performs updates of the client's FQDN and leased IP address information regardless of whether the client has requested to perform its own updates.

To configure a DHCP server to register and to update client information with its configured DNS servers, follow these steps:1. Open the DHCP properties for the server
2. Click DNS, click Properties, click to select the Enable DNS dynamic updates according to the settings below check box, and then click Always dynamically update DNS A and PTR records.
 
• The DHCP server never registers and updates client information with its configured DNS servers.

To use this configuration, the DHCP server must be configured to disable performance of DHCP/DNS proxied updates. When you use this configuration, no client host A or PTR resource records are updated in DNS for DHCP clients.

To configure the server to never update client information, follow these steps:1. Open the DHCP properties for the DHCP server or one of its scopes on the Windows Server 2003-based DHCP server.
2. Click DNS, click Properties, and then clear the Enable DNS dynamic updates according to the settings below check box.  
By default, updates are always performed for newly installed Windows Server 2003-based DHCP servers and any new scopes that you create for them.

http://support.microsoft.com/kb/816592

Please define "outages" and "lose our intranet"; are you actually losing the A records, or are they just not resolving anymore?
If the latter, I suspect that you're using external DNS servers in the TCP/IP settings on your machines. If so, don't. Use only your DC(s) as DNS servers, and configure forwarders on them for external resolution.

10 DNS Errors That Will Kill Your Network
http://mcpmag.com/features/article.asp?EditorialsID=413

Frequently Asked Questions About Windows 2000 DNS and Windows Server 2003 DNS
http://support.microsoft.com/?kbid=291382

Best practices for DNS client settings in Windows 2000 Server and in Windows Server 2003
http://support.microsoft.com/?kbid=825036

yes, you are right, its the latter. When the outage occurs, they are not resolvable but  as soon the IP-lease on the PCs are renewed, they become reachable again.

a little background info.........

Our DHCP server (a linux box) is configured to assign the windows server as the primary DNS and assign itself as the secondary DNS, to all client PCs. In otherwords, both our primary and secondary DNS servers are internal. We have configured a forwarder on the primary to forward 'external' requests to the secondary DNS server.

Sorry i didnt add this initially - our web site is externally hosted and of course the intranet is internal, so requests for the website are forwarded to the seconday DNS server.

The surprising thing is when the problem occurs, both are unavaillable and then they are available again after the ip-renew.

I'm not sure your suggestion will apply to our scenario...pls correct me if i'm wrong.

Thanks.

More background needed:
Do the two DNS servers replicate their zones?
Is your AD domain name the same as your internet domain name?
Whether you can use your Linux machine as DNS server for your domain members depends mainly on whether it supports dynamic DNS (RFC 2136) and SRV entries (RFC 2052).

comment for oBDA

sorry been out of circulation. These are the responses to your questions:

No the DNS servers do not replicate their zones.
Yes our AD DOMINA name is the same as our internet domain name.
The linux box supports DNS (RFC 2136) and SRV entries (RFC2052)

Awaiting your response.