How do I use MAAS and Juju with an existing DHCP server?
You may refer to Manual DHCP configuration in the following link
- https://docs.maas.io/2.1/en/installconfig-network-dhcp#external-dhcp-and-a-reserved-ip-range
There is also a nice document by DELL (Deploying workloads with Juju and MAAS) where you can find a section for using an existing DNS/DHCP server and you can find it here
- http://linux.dell.com/files/whitepapers/Deploying_Workloads_With_Juju_And_MAAS.pdf