Explain DHCP DORA process?



DISCOVER:When a client is configured with the ip setting to obtain Ip address automatically. Then the client will search for DHCP server and the UDP Broadcast to the server about the DHCP discover

OFFER: DHCP Server will offers a scope of ip address available in the pool.

REQUEST: In response to the offer, the Client will requests for an ip address.

ACKNOWLEDGE:In response to the request, server will responds with all Ip address, Mask, Gty, Dns and wins info along with the acknowledgment packet.

Anyone has some more suggestion. You can update it.


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Comments 29 comments

gugan 7 years ago

how the system that requesting ip from dhcp server is getting recognised by the dhcp server.

for ex:

based on mac address etc.

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karthickjck 7 years ago from Bangalore Author

Yes.. with the Source Mac-address

gugan 7 years ago

thank you very much

sushil kumar 7 years ago

Is the protocol used by dhcp is UDP or TCP/IP.

Raakesh 7 years ago

DCHP depends on UDP to carry packets between the client and server tasks.

Refer http://www.faqs.org/faqs/internet/tcp-ip/tcp-ip-fa... for complete information

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karthickjck 7 years ago from Bangalore Author

Sushil.. This protocol can work on both TCP and UDP.

Raakesh 7 years ago

You are correct Karthick. However, from what was understood, Sushil seem to be referring to the DORA process in specific. I believe UDP is being used for this.

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karthickjck 6 years ago from Bangalore Author

Yes.. Raakesh.. You are correct..Its UDP for DHCP..

Rupesh 6 years ago

what are port nos of dhcp?

On which protocols it works?(behind dhcp)

mohan 6 years ago


sasi 6 years ago

Hi kartik how plan to study for this system administrator interview questions like dns dhcp and acitive directory and i have a 1 ? to ask that how to creat a multiple user accounts in ad is there any tool is available or manually v have to type in a exel sheet

Manu 6 years ago

How will the machine know which IP adress it should request for or how will the DHCP server know which IP it should offer to the client.( I believe it has knowledge only about the MAC address )

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karthickjck 6 years ago from Bangalore Author

Hi Manu,

Machine will send an Unicast to DHCP server asking for an ip address. DHCP server will look into its IP Pool and will give one of the IP addresses from the pool to the requesting machine.


Karthick Murugan

Himanshu 6 years ago

can you all please help me

I have perform so many of desktop & system admin. but not selected yet

Can you give me some interview questions for the same

and 1 more thing I wanna ask

If we giong to configure a wireless access point in a network

what type of security we can provide.

1 we can give password for that

along with that can we give any unique thing by which nobody can access the network without permitting by Administrator?



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karthickjck 6 years ago from Bangalore Author

I can help you in ways to secure the Access Point.

Please see my other hub this is applicable for access point as well.


choton 5 years ago

plz give me your update knowledge share

jim 5 years ago

Hi Karthic,

can you explain what are the contents of the DORA packets which are passed between server and client?

Kuldeep Singh 5 years ago

DORA Process

D- Discover

O- Offer

R- Request

A- Acknowledgement

prakash 5 years ago

dhcp client port no 68,server67..i like dhcp its simple concept

Harsha 5 years ago

Great work dude...Thanks a lot!!

syed 4 years ago

what is ARP PROTOCOL and how it works?

selvam 4 years ago

because of this question i loose the interview..thanks for the nice explanation

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karthickjck 4 years ago from Bangalore Author

ARP protocol is a protocol to map Layer 3 address with Layer 2 address. You could see a very good explanation in this link.


bhavne 4 years ago

dw2ed2we 3ref3rf

Bhaskar Dixit 4 years ago

Dear Karthik.

can you tell me please. what is the inside of Discover, offer, request aknowledge

Nazim 4 years ago

Dear Karthick,

If DHCP work on UDP protocol so why send an acknowledgment as per topology of UDP its not send any type of acknowledgment. Please suggest the same.

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karthickjck 4 years ago from Bangalore Author

Its not an acknowledgment for the UDP packet but the acknowledge of the requested IP.

Shankar 3 years ago

Still needs to discover more

natique ali 3 years ago

fantastic its to good

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