last valid host on subnetwork

[philexam]

Hello, I and new to subnetting and currently trying to prepare for the ccent exam. I have the Todd Lammle Study Guide.

Question: can any one explain: What is the last valid host on the subnetwork 172.25.192.0/22, Thanks

[DonB]

A /22 means that we want to subnet the 3rd octet. A /22 also means we will use a block of 4 in the 3rd octet.

the network address is 172.25.192.0
the first host address is 172.25.192.1
the last host address is 172.25.195.254
the broadcast address is 172.25.195.255

the next network would start at 172.25.196.0. Remember that the /22 means that we are using blocks of 4 in the 3rd octet.

[mid4]

When you guys mean subnetwork is that the subnet or the actual host ip address of the broadcast address?

[Fuzz]

A subnetwork, or subnet, is the range of IP addresses that are valid for the network IP/subnet mask chosen. It's referred to by the network address IP and either its netmask or its CIDR notation.

e.g

192.168.2.0 255.255.254.0 or 192.168.2.0/23.

[mid4]

When I work out his question, it shows that the subnetwork address is the network address.

What is the subnetwork number of a host with an IP address of 172.16.66.0/21?

A. 172.16.36.0
B. 172.16.48.0
C. 172.16.64.0
D. 172.16.0.0

/21 is a block 8

172.16.8.0 - 172.16.15.255
172.16.16.0 - 172.16.23.255
172.16.24.0 - 172.16.31.255
...
172.16.56.0 - 172.16.63.255
172.16.64.0 - 172.16.71.255

The answer to the question is 172.16.64.0

Would this be correct, as the subnetwork is the network ip address?

[Fuzz]

That is correct