Thank you for the detailed and to the point answers. One other question: Assuming dhcp-ignore-clid is not set and the clid is unique across all interfaces: Which one is leading for getting the IP address? The mac address or the clid?
With warm regards - Will -----Original Message----- From: Dnsmasq-discuss <dnsmasq-discuss-boun...@lists.thekelleys.org.uk> On Behalf Of Simon Kelley Sent: maandag 24 maart 2025 23:18 To: dnsmasq-discuss@lists.thekelleys.org.uk Subject: Re: [Dnsmasq-discuss] DHCP and DNS regestration On 3/24/25 09:47, support | IT visibility via Dnsmasq-discuss wrote: > Hi *, > > I’m using dnsmasq with a few vlan interfaces and each interface is tagged. > > And running tests with pihole as well as native dnsmasq. > > An example on how this is setup in both cases (.i.e. pihole as well as > native dnsmsaq): > > ===== > > # Wired - vlan 210 > > interface=eth0.210 > > domain=wired.lan,192.168.210.0/24,local > > dhcp-range=set:vlan-210,192.168.210.11,192.168.210.99,168h > > dhcp-option=tag:vlan-210,option:router,192.168.210.241 > > dhcp-option=tag:vlan-210,option:dns-server,192.168.210.235 > > dhcp-option=tag:vlan-210,option:ntp-server,192.168.210.235 > > dhcp-option=tag:vlan-210,option:domain-name,wired.lan > > ===== > > The idea behind this is that devices with multiple vlan interfaces > have their IP’s registered with dhcp and dns. > > The dhcp part seems to work – all interfaces have the correct IP details. > > However, the log has numerous wrong-address errors like this (i.e. > pihole as well as native dnsmasq): > > ===== > > Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPREQUEST(eth0.210) > 192.168.210.201 > bc:24:11:87:be:e5 > > Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPNAK(eth0.210) 192.168.210.201 > bc:24:11:87:be:e5 wrong address > > Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPDISCOVER(eth0.210) > bc:24:11:87:be:e5 > > Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPOFFER(eth0.210) 192.168.210.201 > bc:24:11:87:be:e5 > > Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPREQUEST(eth0.210) > 192.168.210.201 > bc:24:11:87:be:e5 > > Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPACK(eth0.210) 192.168.210.201 > bc:24:11:87:be:e5 osiris > > ===== > > *Question-1*: where are these wrong-address messages coming from? > > If I look at the dhcp.leases (Pihole) or dnsmasq.leases (native > dnsmasq) there is always one entry like this: > > 1743408124 bc:24:11:87:be:e5 192.168.230.201 osiris * > > *Question-2*: why is there only an entry from the last vlan interface > of (in this example) osiris? And not one for every vlan interface? > > *Question-3*: the same applies for dns regestrations where there is > only an entry for the last vlan interface? > > I have tried to force this dns regestration for all fqdn’s for each > vlan using the following settings (i.e. pihole as well as native dnsmasq): > > dhcp-ignore-clid > > dhcp-fqdn > > dhcp-client-update > > expand-hosts > > domain-needed > > domain=lan > > local=/lan/ > > Does the above ring any bells? Any suggestion? > > With warm regards – Will > > Answer 1: Because a lease exists for the relevant MAC address with a different IP address to the address it's requesting. Answer 2: Because the device is using the same MAC address on all the VLANS it's talking through. The MAC address is supposed to be unique: a DHCP server won't allow a MAC address to have more than one lease. Answer 3: Partly the same answer as 2, but even if you use unique MAC addresses (or client-ids) dnsmasq will only associate a DNS name with at most one DHCP lease. That's a design decision. Cheers, Simon. > _______________________________________________ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discu > ss _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
