DHCP client behavior during restart if DHCP server is down

Hello Friends

I hope this post finds you in good health and spirit. Recently I was doing some R & D on DHCP and found some interesting facts about DHCP client during restart. So putting them together in this post for future references. Probably you will also find this interesting.So here the fact

Question: If DHCP client have got IP from DHCP server and enough time is left before lease expire, what will happen if client restarts and the server is unavailable?

Answer: If client is not able to reach server at time of startup, it tries to ping default gateway that was assigned previously. If default gateway responds that client assumes that it is still in same network and hence keeps on using IP address (Remember lease time is still left). If client can’t get response from gateway, it will consider itself to be out of network and hence will auto configure (put APIPA address) itself. Meanwhile, client will keep on searching for DHCP server every 5 mins and once it receive response from server, will abandon APIPA and will get new IP from server.

I did testing to verify above mentioned facts and YES it works like that. Since it’s new and interesting information for me so thought to post it here before losing. Was this new for you too? Asking out of curiosity please don’t get offended. Lol.

“By the way today Pakistan has finally decided that will send their cricket team to India for T-20 world cup. Wow, at-last. Now it’s going to be a good contest”.

Thanks for your time and I will see you soon with another post. Till then “Bye” and take good care of yourself.


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