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HOW TO WORK DHCP?


Dynamic Host Configuration Protocol, a protocol that allows a DHCP server to automatically set TCP/IP network configuration for a client computer.


How does work DHCP?


1.Whenever a client computer boots up, it broadcasts a DHCPDISCOVER massage.

 it doesn't matter where the client is in airport, at home, in a desert, or in a jungle

 it would send this packet looking for a DHCP server. 

 And the client has no idea if there is any DHCP server closeby therefore broadcast the only way you may

notice the destination IP address is 255.255.255.255.

DHCPDISCOVER packet simply says "Hello", is there any DHCP server out there? I want to connect the Internet."

2.supose there is a DHCP server close by and it hears the DHCPDISCOVER massage. the DHCP server responds with a DHCPOFFER massage.

  It is a broadcast UDP packet.

  It simply replies :"I hear you. I can lease you this IP address and this subnet mask, so that you can connect to the local network.

  And I also tell you IP address of your 

  default getaway, and DNS servers so that you can go to internet. your lease is 2 days. of course, you can renew the lease after 2 days."

3.The DHCP client responds with a DHCPREQUEST It simply says: "I accept all these TCP/IP information and I accept lease term for 2 days.

  Thank you very much"

4.DHCP server replies with a DHCPACK Massage. It is basically a acknowledgement packet. It is simply says:" OK let's do these. You go ahead use the network,

  and I register your

  MAC address and IP address and other information in my DHCP database."



Summary.

DHCP is a dynamic way of giving a client computer network connection credentials communications between a DHCP server and clients are broadcast, UDP, not TCP.

The client users port 68, and server users port 67.


Last I want you to try this : start your windows command prompt if you are a windows user, type in ipconfig/release, then

 reload or refresh your favorite browser to see what happens.




Issue:


No internet connection in DHCP Environment:


type in ipconfig/renew, hit enter key and then reload or refresh your browser, you would see the internet is back.


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