how to Calculate Network address from IP address？

[buklu]

for example ip address 172.19.24.5

Network address:

172.19.16.0        how do i find the network address?

 

[Lurick]

Without knowing the subnet mask it's really difficult. If they default gateway starts at .1 then you can maybe figure it out but if it's not the first IP in the subnet then it's going to be hard to do anything other than guess.

[NinJake]

If you knew the subnet mask, I'm assuming its 255.255.0.0 then that lets you know where the network address is compared to the host address.

[buklu]

17 minutes ago, Lurick said:

Without knowing the subnet mask it's really difficult. If they default gateway starts at .1 then you can maybe figure it out but if it's not the first IP in the subnet then it's going to be hard to do anything other than guess.

subnet mask 255.255.240.0

[Sir Asvald]

11 minutes ago, buklu said:

subnet mask 255.255.240.0

That would be a /20

[buklu]

Just now, Abdul201588 said:

That would be a /20

yeah,i know /20,but i don't know how to find out the network address

[Ralphred]

The network address is the 1st address within the subnet, do not confuse this with the first usable host address.

So for 172.19.24.5/20 172.16.0.0 is the network address and 172.31.255.255 is the broadcast.

 

The main assumption is that if you break down a network into smaller subnets, let's say by creating a 10.x.y.z/24 network, you don't stamp on neighbouring address spaces by making z, in this case, anything other than 0. If you were going to create a /25 network you wouldn't make z anything other than 0 or 128.

So back on topic, if I have a nic with an ip of 192.168.1.253/30 the network address is 192.168.1.252 (1st address in the subnet) and the broadcast is 192.168.1.255 (last address in the subnet). Lots of people ignore the the first and last addresses, until they start doing things with inter network routing or broadcast.

[Zergom]

Quote

The network address is the 1st address within the subnet, do not confuse this with the first usable host address.

So for 172.19.24.5/20 172.16.0.0 is the network address and 172.31.255.255 is the broadcast.

That's not correct. For 172.19.24.5/20 your first IP would be 172.19.16.1 (technically .0, but that's bad practice as it's usually used as an identifier) and the broadcast would be 172.19.31.255, leaving 172.19.31.254 as your last usable IP. Here's an easy to use subnet calculator.

 

To answer OP's question, your network would be 172.19.16.0/20.