Ask the Expert

What is the broadcast address used for?

What is the broadcast address (or the Network address with the invers of the Netmask) used for?

This is what I know so far:

    Requires Free Membership to View

is used in arp to get the hardware (MAC) address of the target." Doesn't make sense: If the target is listening on both the BROADCAST and it's IP addresses, the source might as well use the target's IP address in order to ask the for the MAC address from the target.
IP and MAC addresses are both needed. If you use the analogy of sending a letter, both a physical street address and a logical name are needed to complete delivery. A network operates in much the same fashion.

The network stack is implemented in layers. The most common method used to explain its operation is the OSI model. Toward the bottom of the stack are the physical layer protocols. An example of a physical layer protocol is Ethernet. Ethernet nodes are identified by MAC address. MAC addressing is the method of communication used to communicate on a LAN.

Higher up the stack are logical protocols. An example of a logical protocol is IP. Therefore if IP needed to send information to the gateway router in must pass the data packet down the stack to the NIC. This resolution of a known IP to an unknown physical address is known as ARP. Since the NIC does not know the physical address of the gateway router, it performs an ARP to determine the gateway routers physical address. Once this information is returned, the packet can be addresses with the gateway routers MAC address and the packet can be sent out on the wire. Most systems cache this information so that an ARP does not have to be performed each time a packet is transmitted.

This was first published in August 2003

There are Comments. Add yours.

TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to: