Did you know, there are two tastes of Broadcast Addresses?

-              -              The first broadcast address, has the shape of 255.255.255.255

o   This type is used in scenarios such as DHCP Discovery, when a client tries to communicate any DHCP server that’s out there to get an IP address

o   The destination IP address in the frame is the broadcast address “255.255.255.255”

o   This type only used within the LAN (most the cases)

o   To know the impact of the 255.255.255.255 broadcast address, let’s try out a small test

§  Go to any machine in your network, let’s be a Windows machine

§  Go to the command prompt and type: ping 255.255.255.255

§  Now every and each IP device in your LAN will reply the ICMP echo request with an ICMP echo reply back to the windows machine

-                 -          The second broadcast address, has the shape of 192.168.2.255 (if the network is 192.168.2.0/24)

o   This type is used in scenarios such as WoL (Wake on LAN), in which you can power up any machine under your administrative control

o   In the below illustration, we have two VLANs (VLAN1 and VLAN2) separated by a router in the middle. We also have a WoL server in VLAN1

o   In case the WoL server needed to send a “Wake up packet” to all the end points in VLAN1, it’ll use a broadcast address of 255.255.255.255. But, in order to send “Wake up packet” to the end points in VLAN2, it craft a frame with a destination IP address of “192.168.2.255” , for it to complete its job

o   This broadcast is called “Directed Broadcast”