Okay, so the next subnet is 1 9 2 1 6 8 1 64 slash 26.
I'll copy the previous example but remember this is actually a different subnet now.
The subnet address is slash 64, so we'll need to update these values in the last octet.
So to work out the first host you simply add 1 to the subnet portion, subnet portion is 64.
So 1 added to that is 65.
The next subnet is 128.
So going back to our original example, this is the second subnet.
This is the third subnet, 128.
That means that the broadcast for the subnet is 127 because 128 minus one equals 127.
This is the next subnet minus one gives us our broadcast for the current subnet, last IP address in the
subnet is 126.
Next one is 125.
Next one is 124.
So there is our subnet broadcast for second last host and third last host.
I haven't rechecked the binary.
You could do that if you wanted to.
I'm simply using a quick method to work out the IP addresses so this router needs to be configured with
the first IP address on the serial interface, so interface serial 0 1 0, no shut, IP address 1 9 2 1 6
8 165 uses that subnet mask.
So again it's just one more than the broadcast address, show IP interface brief there's the IP address
on the serial interface on the Internet router, we need to use one less than the next subnet so 127, show
IP interface brief on the first serial interface, interface serial 0 1 0, no shut, IP address 1 9 2 1 6
8 1 126 with the subnet mask, 127 is the broadcast one less than that gives us our last IP address, So
can we ping 1 9 2 1 6 8 1 65? Yes, we can.
So that's great.
We have IP connectivity between this router and the Internet router and notice an OSPF neighbour relationship
has come up, the routers were pre-configured with OSPF, so hopefully this router can now ping the
DNS server on the Internet and notice it can. On PC 1, can it ping the DNS server? Yes, it can.
If I trace to the DNS server traffic is going to router 1 on the Ethernet interface then it's going
to the Internet router on the serial interface then to the Internet.
The reason it works is, this router has been pre-configured with OSPF but is also being pre-configured
with Network Address Translation. This lab is concentrating on subnetting so I pre-configured the NAT
and routing protocols so that you didn't have to worry about that.
Can we get to cisco.com?
Yes, we can.
Can we get to facebook
.com? Yes, we can.
So that works on PC 0.
What about PC 2, can we get to cisco.com?
Yes, we can.
Can we get to facebook.com?
Yes, we can.
So I'm hoping you're ready at this point, you've learnt a lot about IP addressing, subnetting, how to configure
it and how to make it practical in a network. In the next video
I'm just going to continue doing something very similar for the other subnets and I'm going to speed
it up by using tricks rather than binary.