How DNS and DHCP Servers Communicate (With wireshark)

In this video I explain how DHCP work and how it updates DNS entries for new hosts joining the network. I'll also mention Zero Config
0:00 Intro
1:00 the Network configuration
6:00 Showing DHCP in Wireshark
6:30 DHCP Discover
14:40 DHCP Offer
19:00 DHCP Request
21:30 DHCP ACK
22:00 How DHCP Updates DNS
26:15 Zero Configuration (mDNS, Link-local)
Resources
Dhcp datatracker.ietf.org/doc/html...
Dynamic updates , dhcp RFC2136
datatracker.ietf.org/doc/html...
www.cisco.com/c/en/us/td/docs...
RFC 1497
www.rfc-editor.org/rfc/rfc149...
www.rfc-editor.org/rfc/rfc676...
Link-local
www.rfc-editor.org/rfc/rfc3927
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Stay Awesome,
Hussein

[@hnasr]

Get my fundamentals of network engineering course network.husseinnasser.com

[@KaranSharma-ew7io]

Your talks are top notch

[@andreffrosa]

11:07 you can't do that by default because most home routers don't have a local DNS, they just send to you the ISP's DNS resolver (or the one you configure in the router). The reason you can do that is because yo have bonjour (on apple) or havai (on linux and maybe windows), which don't even require a local dns server and are the implementartion of mDNS which you mentioned on the last past of the video. So this only works in networks where the DCHP server and the DNS server co-exist and the DHCP server is aware of this. Good video by the way

[@prostem9500]

Love the use of Wireshark in this video, It really helps understanding the subject. Hope you continue with it.

[@Heyfa]

Really appreciate your content and the way you explain, and break down, concepts. Thank you so much

[@AllMightGaming-AMG]

I just love the way you communicate, and how you dump your whole thought process! Can you explain how public IPs work? I mean how a dedicated public address is attached to a machine behind router(s) or NAT(s)?

[@farzadmf]

SUUUPER nice video, great walkthrough and explanation, LOVED it!

[@HarshKapadia]

Really interesting! Thank you Hussein!

[@darpanmalhotra2]

Just to make it complete: DHCP server adds RR dynamically when lease is assigned. Also, when the lease expires (i.e. 4h in this case), DHCP server removes the same RR.

[@matnexmix6922]

Niceeeeee, top-notch content Hussein... Why did the client send a broadcast again for the DHCP Request... 🤔🤔 Since it already knows the DHCP's IP address...? I'm curious 🧐

[@Thank_Me_Later]

Hi 👋 I have a confusion that should I enable or disable 'DNS Relay' option in my router ? What exactly it is? What is the use .... If u make a video regarding this will be helpful ❤️

[@anushree3744]

@Hussein Waiting for your explanation on the New revised architecture of twitter shared by Elon

[@tariqosman5811]

💚💯💯👌👌🙏

[@esmaelmohamed8209]

How could I become a member Hussein?? I mean PayPal not working from Ethiopia

[@karanshah838]

What happens if 2 devices have the same host name ? Will the connection to the router not happen ? If the connection to the router happens who will the packets be sent to ?

[@TheAddictioneer]

I’d say it’d follow the same DNS behaviour when two A records pointing to different IP Addresses. It’ll round robin. In work environment, Server admins will be the one controlling hostnames and A records.

[@darpanmalhotra2]

It boils down to de-duplication policies defined on DHCP server. A simple policy could be: husseinmac2.home.local, husseinmac2-a.home.local, husseinmac2-b.home.local, husseinmac2-c.home.local

[@abdirahmann]

this video kzbin.info/www/bejne/aqrYhWiBh5yHiMU will explain how a rogue dhcp attack can be prevented with a combination of port security and dhcp snooping. i really love and i respect that guy very much, he is a double CCIE. mad stuff!