IT 3110



Dynamic Host Configuration Protocol

What does it do?

DHCP components

DHCP Procedure (DORA)

DHCP Details

DHCP Details

DHCP Lease renewal

DHCP Leases

Every time a client device restarts within the lease period, it contacts the configured default gateway. If the gateway does not respond, the client considers itself to be on a new subnet and enters the discovery phase.

Clients will redo DORA when they detect they are on a new network.


Types of Leases


DNS expects known ip addresses. DHCP can cause IP addresses to change. How to make sure DNS records are the ones that DHCP has served out? DNS dynamic update: dhcp will make modifications to your DNS entries.


DHCP is used with IPv6… but it works a little differently.

Goal (your assignment may be different)


If you clone a vm (bionic) and get a dynamic dhcp address, you might have the same machines negotiating for the same address. Check the /etc/machine-id on each machine. if they are the same, you have a problem. To fix, you should delete that file and then run: sudo dbus-uuidgen --ensure=/etc/machine-id. Then sudo netplan apply. Then check to make sure that the machine-id’s are unique.