Now let's turn our attention to Dynamic Host Configuration Protocol,
or DHCP itself, particularly as it relates to the Windows Server role.
The AZ‑800 exam mentions DHCP scopes and reservations.
We're not going to do a full work up of DHCP.
If you need remedial instruction on this,
I would suggest you consult the Pluralsight library. Of course.
DHCP is a way to automate the distribution and update of
IPv4 and IPv6 addresses. It could be either public or
private, but the only in my career,
the only time I've ever seen DHCP is with private
non‑internet routable address ranges. And a scope is simply
an administrative IP address grouping.
The most common scenario is that you'll have a scope for each subnet.
And I mentioned earlier that DHCP is a broadcast‑based protocol, and if
you know much about TCP, IP, and Ethernet,
a broadcast domain is aligned to an IP subnet and you have router
interfaces that are routing traffic among those subnets.
And normally, routers will drop all broadcast traffic.
So, in Windows Server, you can deploy the DHCP relay agent to
get your DHCP traffic through router interfaces and to
support multiple subnets; otherwise,
it's something you can configure on the router itself, the
so called IP helper address. You can set scope options, a
couple different levels in DHCP.
So the idea is that you've got client devices,
not so much servers that are going to need a static address,
but you've got client or endpoint devices that need an IP
configuration when they come online.
And if you're doing multi scopes on multi subnets
based on where the request originates,
the DHCP server will offer a lease from a scope that matches that subnet ID.
And in addition to your IP address and subnet mask,
you can deliver really a full complete configuration to the client.
This is something you can deliver at the server level in which those
options go to all scopes, or you could do scope by scope. You might do a
scope by scope default gateway, for example, and you might deliver DNS
server addresses at the server level.
You see what I mean?
Even more granularly, DHCP supports what are called user and vendor classes.
Now I tend to stay away from the user classes because they're more
proprietary, vendor classes are much more cross platform and open.
But essentially, this allows you to get even more granular. I mean the
scope option is going to apply to all leases or reservations on that
entire subnet. You might have even more specific options for particular
devices, maybe based on vendor. For users,
you could separate user accounts and deliver DHCP‑specific options there.
Now, we're not going to get that deep into it, I just want
you to understand that that capability exists. Reservations
are much more common in DHCP.
This is a hard‑coded MAC address, the burned‑in address on your
network interface to a specific IP address. Now, you could create
reservations for your Windows Server infrastructure servers if you
want to manage their IPs, in say IPAM, but at the same time,
ensure that those systems always have the same address for them.
That can create problems though because a lot of times the service that
you're running on the server needs a static address.
So in my practical experience,
I see reservations more for things like network printers and other
appliance‑type devices where you want to centrally manage the IP address
and potentially update it, but for the time being,
that device needs to be on a static, non‑changing IP address.
And lastly, as you saw in the demo,
IPAM can be really instrumental in managing reservations
and managing DHCP and managing DNS. It's a really good service.