new at this, what is the additional hex?

[travisariastrc65148]

I have a question about what the additional hex characters are at the end of the mac?

0100.5056.b3ed.d8

my professor was having a problem remembering and I am curious now anyone able to let me know or help me with finding the information for identifying the end characters?

[Elliot Dierksen]

That is for a DHCP binding, not an ARP entry. Correct? I don't know if it is the router DHCP server or the client that is prepending the "01", but I have seen that more than a few times.

[paul driver · Accepted solution]

Hello
The original mac address is 0050.56b3.edd8 which will be the client identifier in any dhcp requests the host makes, however as already noted when a static dhcp reservation is created on a cisco router/switch then you need to append 01 in front of client identifier so to state the media type of the interface the client is attached to.

So now the full dhcp client identifier will read <--0100.5056.b3ed.d8

[travisariastrc65148]

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Thank you very much 🥰 thank everyone for the help but I believe this is the best answer I have received and am very thankful to This community of networkers for all your help! Can't wait to be as knowledgeable as you all one day! Health and safety to all of you and have a wonderful year.

[Giuseppe Larosa]

Hello @travisariastrc65148 ,

as explained by @Elliot Dierksen and @paul driver actually there is an hex 0x01 prepended to the true MAC address.

This value should only mean the client is on ethernet as it identifies the media type.

0x01 -> media type is ethernet

the DHCP client-id is built by prepending the media type byte to the original MAC address.

Hope to help

Giuseppe