As you can see from the official documentation, those parameters (network
and broadcast
) are not required.
In fact,
(network, broadcast and gateway are optional)
In your example, your network would be 192.168.5.0/24
and your broadcast 192.168.5.255
. These can be derived from your address
and netmask
parameters. To understand these parameters and how to determine them, you need to read up on IP subnetting.
In my opinion, the network
and broadcast
parameters can usually be omitted.
Quick primer
In IP, you usually have an address (192.168.5.101
) and a netmask (255.255.255.0
).
The netmask explains how many of the bits in the address refer to the network and how many refer to the host. In this example, it's 24bits (that's what the netmask means, and that's what the /24
means which you often see in this context).
These 24bits are exactly the 192.168.5
part of your address. This means, all machines with an address, that starts with 192.168.5
and a netmask of /24
, are in your same network.
The remaining part (the 101
) is your host part. It identifies your single machine.
When taking an address and fill the host part with zeros (in binary), that is equivalent to the network (so, 192.168.5.0
). If you fill the host part with ones (in binary), you get the default broadcast address (192.168.5.255
).
![enter image description here](../../I/static/images/b5ba526dd35c83df0bc1fbde1f4058bfb95a5f5b75f3c4acc7a4ce115f630140.png)
Source
I just ran some tests it seems there's a consistent 1ms slower response with a ping when they are not there – user64908 – 2012-07-05T15:12:49.993
1@user64908, a performance difference seems extremely unlikely. The applied network configuration will be exactly the same unless you supplied and invalid/unusual network/broadcast. – Zoredache – 2012-07-05T16:08:50.030