[Dnsmasq-discuss] DNS Helpers

[Alex Morris]

On Sun, 13 Sep 2026, at 23:05, Sean Kelly wrote:
> 
> Hello. THis may have already been addressed. Sorry if this is a duplicate.
> Cisco modeling labs CML comes with a dnsmasq instance. I am trying to use
> it as a dhcp server and in one vlan it works great. What I cant seem to
> make work is a dhcp service for devices oth other layer 3 networks. Is
> dnsmasq capable of delivering IPs to multiple networks without having a
> network presence in them?
>

Yes. You need a separate "dhcp-range" entry for each subnet. The "set" and "tag" options help here. See the "-F, --dhcp-range=" section of https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

For example:

##################################
#
# DHCP range 192.168.100.0/24
#
##################################

dhcp-range=set:100,192.168.100.100,192.168.100.250,255.255.255.0,1800s
dhcp-option=tag:100,3,192.168.100.1

##################################
#
# DHCP range 192.168.123.0/24
#
##################################

dhcp-range=set:123,192.168.123.100,192.168.123.250,255.255.255.0,1800s
dhcp-option=tag:123,3,192.168.123.1



-- 
Alex