ddns updates for reserved (fixed-address) IPs

John Miller johnmill at brandeis.edu
Fri Feb 7 17:00:55 UTC 2014

On Fri, Feb 7, 2014 at 11:47 AM, Simon Hobson <dhcp1 at thehobsons.co.uk>wrote:

> John Miller <johnmill at brandeis.edu> wrote:
Thanks for the reply, Simon.

> > In my test system, it appears that if an address is part of a dynamic
> pool, its associated DNS records will be deleted when the IP is freed for
> use.
> Correct
> With hosts configured using the 'fixed-address' parameter, however,
> associated DNS records do not appear to be deleted when the host in
> question has its lease expired.
> They aren't added by default either. Host statements with a fixed address
> do not result in a lease being created, by default there is no DNS update,
> and because there is no lease to expire there will be no DNS removal at the
> end of the lease.

Gotcha.  So using "update-static-leases" will result in names being
created, but since there is no lease, the names will not be deleted?

> > ... if we expand a dynamic pool to include some previously reserved
> addresses, do we then need to manually clean up DNS to remove the old
> fixed-address A and TXT records?
> Yes
> However, current versions now support a "reserved" status for a lease. The
> only way to set it is to add the reserved keyword to a lease - either by
> editing the leases file (or using OMAPI ?). But once set, the lease then
> behaves as any other lease (DDNS updates, lease expiry etc) apart from
> being tied to a specific client.
> For some uses, this may be more appropriate than host statements.
Indeed it does sound more appropriate than using existing host blocks.
I'll give this a try right now and see how it works.  Thank you for the

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