A hub transmits all incoming messages to all of its ports except the port where the messages came in. A switch usually sends messages only to the destination computer. What information does a switch collect from messages crossing its interfaces so it knows where to send data in future transmissions?

An Ethernet frame has the header, data and trailer and there are two specific fields in the header that helps the switch to know where to send data in future transmissions.

destination MAC address
source MAC address

every Ethernet frame has this and when the frame hits a switch or any device, any device can look at it ( an Ethernet frame ) and know where it is suppose to go and where it came from.

Every switch has a MAC address table where it stores MAC addresses of different computers on the network.

Example:

When a PC1 sends a frame to PC2 through a switch, the switch looks at the header of the Ethernet frame for the source mac address and adds the source MAC address to its MAC address table and also the port that it came through.

simply put:

A switch looks at the source MAC address to see if it knows it already, if it does. Great! no need to add it again to it's address table.

If it doesn't, it adds it's source address and the port that the frame came from.

This basically how the switch populates its MAC address table.

SerenaBochenek SerenaBochenek · Answer 2 · 2020-01-02T08:50:00+01:00

Answer:

The correct answer to the following question will be MAC Address.

Explanation:

MAC Address: MAC (Media Access Control) Address, is an address that uniquely identifies every device on the network. Each address is separated by a colon and consists of six sets of two-two character.

As we know, a switch collects all the information sent by a hub and transmits it to the designation but it takes a look at the MAC address of the source to see it is already in the address table or not.