stuck up record in DNS

Simon Hobson dhcp1 at thehobsons.co.uk
Sun Aug 11 20:10:45 UTC 2019


Nepryakhin Ivan <nepryakhin at speechpro.com> wrote:

> I'm encountered with a strange issue:

See below - it's "correct" operation for your example

> cuted of the file dhcpd.conf:
> 
> ## DDNS related configuration
> 
> ddns-update-style interim;
> ddns-rev-domainname "in-addr.arpa.";
> ddns-domainname "tsc.";
> update-static-leases on;
> 
> group {
> 
>         option routers 10.10.10.1;
>         ddns-hostname = host-decl-name;
> 
>         update-optimization false;
>         update-conflict-detection false;
>         
> 
> # example host 
>             host host12 {
>                 hardware ethernet 18:31:BF:xx:xx:xx;
>                 fixed-address 10.10.10.111;
>         }
>         
> }

Where you have a host entry, the lease does NOT go through the normal lifecycle - and would not normally appear in the leases file.
Without the "update-static-leases on" statement, there would be no DNS update at all. With it, the DNS will be updated every time the host is leased that address - but those DNS records are never removed. Normally, the admin would be expected to add their own DNS entries to match host entries - the "update-static-leases on" statement is really just to save work.

If you want a "fixed" address for a host, and you want the DNS to be added/removed as required, then there is one option available. Add the "reserved" flag to a lease for the host - this fixed the lease so that it will not be allocated to another host. The lease is in all other respects the same as any dynamic lease.



More information about the dhcp-users mailing list