Dynamic updates to DNS from hpux host.

[Andrew_4]

Hi all...

I'm getting rather confused about this now, and I thougth I would ask you all...

From http://www.software.hp.com/products/DNS_BIND/index.html --- It looks like BIND 8.1.2 (with version 1.3 update) supports Dynamic DNS updates...

Okay, so that's fine... But, what does this actually mean ?

Does it mean that you can configure your DHCP server to notify and dynamically change the DNS when it allocates IPs to hosts?

Or does it mean that the DHCP client (ie HPUX node) actually notifies the DNS by itself of its new IP address...

Or does the DNS detect that a node has changed IP ?

Or does it mean you can just, even so often, run this 'nsupdate' tool to update your DNS with the current DHCP allocations...


I've looked at RFC2136, which defines Dynamic DNS updates, but it still isn't clear...

Does anyone know how this works ?

Thanks in advanced... (points will be given)

Andrew

[Christopher Caldwell]

It means that instead of secondaries waling on primaries to check for updated zones, the primary will "notify" the secondary that an updated zone is available.

Performance is improved, and the updates of the secondaries are more timely. (i.e. you don't have to reload the secondary to get it to pick up the new zone).

[Christopher Caldwell · Accepted solution]

Doh! Sorry, I gave you DNS NOTIFY not dynamic DNS.

From a tech document on dynamic DNS:
Dynamic DNS update allows the DHCP server to tell the DNS server or servers when a name-to-address association has been created or changed. When a host obtains a lease for an address, the DHCP server tells DNS to add it to its database. When the lease expires, or when the client gives up an address, the DHCP server tells DNS to remove the association. In normal operation you, as administrator, do not have to reconfigure DNS, no matter how frequently the clients' addresses change through the use of DHCP. The DHCP server uses the host name that the client computer provides.

[John Bolene]

From the documentation:

Support for DNS change Notification (RFC 1996).
The DNS NOTIFY transaction allows master servers to inform slave servers when the zone has changed - an interrupt as opposed to poll model. This interrupt model will typically reduce propagation delay while not unduly increasing the master server's load.


The DNS update is defined as

Using this specification of the UPDATE opcode, it is possible to add or delete RRs or RRsets from a specified zone. Prerequisites are specified separately from update operations, and can specify a dependency upon either the previous existence or nonexistence of an RRset, or the existence of a single RR.




So, if the DHCP server supports this standard, it can send updates to the DNS server.

[Bill Thorsteinson]

If your DHCP server doesn't support dynamic updates,
it is possible to use the lease file to generate periodic
updates as well. Make sure you trust your clients.

You may also want to create a separate domain for
dynamic DNS clients. Otherwise you risk having a client
hijack a servers name.

[Andrew_4]

Thank you all for the help ! My questions have been answered...

Sorry for the delay in assigning points, i've been away...

Have a good day !

Andrew