Skip to main content

What's the deal with DHCP Option 82?

During my review of the Infrastructure Security section of the 300-115 Cisco exam, I was a little confused about the purpose of DHCP Option 82. Why would the controller (or other relay agent) need to check that option before forwarding the DHCP request to the server? This didn't click until I read Cisco's configuration guide on this. Here's how it works:

DHCP Option 82
Step 1:
Configure Option 82 in the DHCP server

Step 2:
Configure the relay agent with appropriate Option 82

Step 3:
Client requests a DHCP address

Step 4:
The DHCP relay agent adds option 82 information before encapsulating the DISCOVER into a Unicast packet to the DHCP server

Step 5:
The DHCP server receives the relayed request, checks Option 82 and sends OFFER accordingly.

Step 6:
The relay agent receives the OFFER, strips Option 82 info (deploys policy if-applicable), then forwards IP address assignment to the client.

If you're studying the topic, I hope this helps.

Comments

  1. Stacked Wild – A stacked wild is actually a series of untamed symbols that appear in consecutive positions on a reel. Stacked wilds can appear as a bigger symbol that may cover a whole reel, or they will take the type of 우리카지노 numerous regular wild symbols in succession. It has been mentioned; Slot gamers don't lose end result of|as a result of} they by no means win; they lose end result of|as a result of} they do not stop when they're forward... Ian wrote to Disabled World to tell us of his experience playing in} on-line Caribbean Poker.

    ReplyDelete

Post a Comment

Popular posts from this blog

VACLs

First time I heard about VLAN Access Lists (VACLs) I was pretty intimidated. What's this access-list that can affect traffic at the L2 level? Must be pretty fancy, huh? Turns out not so fancy. The problem: Under normal operations, ACLs can only filter traffic at L3 (i.e. they have to be applied to an interface in a specific direction. The solution: VACLs use ACLs too, but they stand on the powerful shoulders of the Access-Map format (Route-Map-Looking statements). Configuration Steps Create an ACL Create a VLAN access-map and specify an action Apply the access-map to a SVI Configuration commands: ip access-list extended vacl_test permit ip host 10.1.1.1 192.168.2.0 0.0.0.255 exit ! vlan access-map vacl_test_map match ip address list vact_test action drop vlan access-map vacl_test_map 20 (the 20's just a sequence number) action forward exit ! vlan filter vacl_test_map vlan-list 1 Warning: Note that there may be a need to apply another ACL in the

Passing the CompTIA Network+ certification

Intro: I passed my Network+ (N10-005) on August 26 th 2015 after intensively preparing for 1 month. Ideally I wanted to give myself more time since I was taking 12 credits that summer in college and working full time but I had just learned that the exam that I had been familiar with through my Networking class at the Community College was retiring at the end of November, so my only choice was: to either take the N10-005 or dedicate a few more months to familiarize myself with the topics in the N10-006 – time that I didn’t have. So I decided to go for it. Scheduling the exam: Naturally I wanted to schedule the exam when I felt ready, but then I figured I would never “feel” ready. I realized that I had to push myself to do it, otherwise it wasn’t going to happen. So I decided to schedule it for the end of August, giving myself just one month to prepare. I did a quick online search since I wanted to purchase a discount voucher, got one from GetCertifiedForLess  at $246 (