-: Subnetting.
Subnetting is the act of creating subnetworks logically
through the manipulation of IP addresses.
So, if I take a large chunk of IPs,
like a 256 block, I can break it down
into four blocks of 64 IPs,
or eight blocks of 32 IPs,
however you want to break it down in your subnetting,
which you learned back in Network+.
Now, subnetting has some benefits to our network.
First, it allows us
to more efficiently use the IP address space
that we've been given,
and it's going to reduce the broadcast traffic
and the number of collisions,
because there's less hosts on any given network.
But, it also can increase our security
by making our networks more compartmentalized
and allows them to be in smaller sections.
Any time information wants to go from one subnet to another,
it has to be routed through.
And that gives us an additional place
to place access control lists
and other things to our router
to give us additional security.
Now, you can use subnets to help secure your network
by doing a couple of different things.
First, you want to assign different policies
to each subnet.
For example, I might have a subnet that's associated
with my printers,
and those have different policies
than the ones associated with my servers,
and those have different policies
than the ones associated
with my office workers' desktop computers.
Each of those can have different policies
for each subnet.
Also, you want to be able to monitor all of your subnets
and check the traffic that's going into and out of them.
By using subnets, we can help isolate an attack, as well,
because all traffic has to be routed
before it can enter or exit a subnet.
And therefore, if somebody breaks into, say,
the secretary's computer, they're going to be trapped
in that subnet, unless they have permission
to go into some of the other more secured subnets
that we have out there.
Each time it goes through a router again,
it's going to be checked by the access control list,
and that secretary's laptop may not have access
to the database server, for example,
which has more confidential and secured information.
So, they're going to be limited in what they can do
once they've broken in.