We're Sorry, Full Content Access is for Members Only...

If you like to keep on reading, Become a Member Now! Here is why:

  • Learn any CCNA, CCNP and CCIE R&S Topic. Explained As Simple As Possible.
  • Try for Just $1. The Best Dollar You've Ever Spent on Your Cisco Career!
  • Full Access to our 651 Lessons. More Lessons Added Every Week!
  • Content created by Rene Molenaar (CCIE #41726)

469 Sign Ups in the last 30 days

100% Satisfaction Guaranteed!
You may cancel your monthly membership at any time.
No Questions Asked!

Tags: ,

Forum Replies

  1. This is best explained with the following two captures:


    Above you can see the ARP request. The sender (fa:16:3e:38:94:94) creates the ARP request and is looking for It encapsulates this in an Ethernet frame with its own MAC address as the source and destination broadcast.

    Everyone on the subnet will hear this message, the device that has the destination MAC address will reply:


    ... Continue reading in our forum

  2. sir , for the scenario
    Computer A ——-Switch1—–ROUTER1——————ROUTER 2 —- Switch2 —– Computer B.

    you said that

    "Computer A will do an ARP request for the IP address of Router 1

    Computer B will do an ARP request for Router 2 (its default gateway).

    Router 1 and Router 2 will do ARP requests on the link that connects them to discover each others MAC addresses."

    please rectify/guide me if i am worng
    computer A will send ARP request to R1 to know R1 MAC address, so whenever it sends send data to ComputerB it will then send it to MAC address of R1.

    sir my second query i

    ... Continue reading in our forum

  3. Hi.

    Router A wants to know MAC address of router B. So, it broadcasts ARP. Only router B replies.
    In this case, target MAC should be FF:FF:FF:FF:FF:FF which is broadcastin ARP request. Why the target MAC is all 0’s in ARP request?

  4. Thanks Lazaros, your explanation has been very useful. Now is more clear for me.

  5. Hi Braulio,

    Every device that has an IP address builds an ARP table. They somehow need to map a L3 IP address to a L2 MAC address.

    A computer (host) will have an ARP table. A switch that you configure with an IP address for remote management also has an ARP table.


96 more replies! Ask a question or join the discussion by visiting our Community Forum