Multiple subnets across different vlans

Chris Buxton chris.p.buxton at
Sun Jul 10 01:48:15 UTC 2011

On Jul 9, 2011, at 1:27 AM, Simon Hobson wrote:

> The easy answer is to remove all the existing A records and wait for them to be repopulated. The tricky bit is that if there are clients that have had A records added by the ISC server, you'd need to edit their leases so that the server will re-add them at the next lease renewal.

Or turn off update optimization, wait for a full lease duration, and turn it back on (or remove the setting). Restart dhcpd each time the settings are changed, of course.

> On that, you haven't mentioned your network topology - in particular how the DHCP server is connected. Is it connected to a trunk, with a VLAN interface for each VLAN; or is it connected to one VLAN with a DHCP Relay Agent somewhere (possibly in the switch) to get DHCP packets from/to the other VLANs ? It is possible to misconfigure stuff so that a machine sees traffic it shouldn't and/or appears to be on the wrong VLAN.

Actually, the OP's original post showed one network reaching dhcpd via a relay, while the other was directly connected.

On Jul 8, 2011, at 5:57 PM, Joshua Beard wrote:

> DHCPREQUEST for ( from 00:50:41:72:5d:01 via eth0: wrong network.
> DHCPACK on to 00:25:4b:b8:27:7e (HS01303S4418) via

Chris Buxton
BlueCat Networks

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