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So in a general sense (e.g. not windows, linux specific) what network traffic is generated when I first boot up/plug in a network cable.

Basically:

  • Detect DHCP server
  • Pull an IP Address from DHCP
  • ARP to detect default gateway's IP address

What am I missing? Am I in the right order?

Thanks

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closed as not constructive by Michael Hampton, mulaz, ewwhite, GregD, Sirex Jan 13 '13 at 21:21

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1 Answer

There is a good deal that could potentially be going on at boot. But, it seems that you are interested in what happens when to get a DHCP address, so I will speak to that specifically.

First, when a machine comes up to the point that the DHCP client is ready to get an IP address, a DHCPDISCOVER message will be broadcast to the local subnet. If there are any DHCP servers on the network they will respond with a DHCPOFFER to the client. This will contain an offered IP address and a lease duration at the bare minimum. Generally a gateway, dns servers(s) and a possibly a few other DHCP Options will be specified.

This is a very very basic description of what happens and what is possible with DHCP, you should really read the DHCP RFC for more detail on how it works.

ARP is a protocol that is designed to translate IP address to MAC addresses for Layer 2 communication and isn't involved in the handing out of IP addresses any more than DNS is involved in loading a web page.

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