IPv4 Addresses 5

By certskills September 14, 2012 08:00

More practice practice practice! This time, you get some basic IP addressing requirements. Your job: calculate the IP addresses to be used by routers and hosts, and create the router configuration for in the interfaces in the network diagram. No guile, no tricks, just a chance to exercise.



This lab asks you to configure all the router IP addresses for the design shown in Figure 1, given a set of requirements. At this point, do not configure static routes or a routing protocol; just configure the IP addresses per the following specific instructions:

  1. Use the subnets as listed in Figure 1.
  2. Routers must use the highest IP address(es) in each subnet.
  3. If more than one router exists in a subnet, the router with the higher number in the hostname gets the higher IPv4 address. EG, R3 would have a higher IPv4 address than R2.
  4. Hosts should use the lowest IPv4 address in the subnet, with the same tiebreaker concept as stated in #2.

Figure 1: Router Triangle with IPv4 Subnets


Table 1 shows a way to organize the addresses for reference.

Table 1: IPv4 Addresses

Location Address/Mask
R1 F0/0
R1 S0/0/0
R1 S0/0/1
R2 F0/0
R2 S0/0/0
R2 S0/0/1
R3 F0/0
R3 S0/0/0
R3 S0/0/1


Are You Ready? Config Speed
Answers: IPv4 Addresses 5
By certskills September 14, 2012 08:00
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September 19, 2012 9:01 am

[…] Original Problem Statement […]

November 27, 2013 9:51 am

Hi I purchased the Cisco CCNA Routing and Switching 200-120 off Amazon how can I download the material that came with the printed book

December 3, 2013 6:24 am

I am assuming you bought the Amazon Kindle, not the printed book? And you’re asking about the content that normally comes with the DVD in the print book? If so… look at the last page in the Kindle eBook; it details how to download the DVD content. However, note that Amazon does not support the process that distributes a license code, which then allows access to the practice test software and exams. The rest of the DVD content is available, however.

December 30, 2016 9:00 am

Hi Wendell – I think this exercise is a little confusing. The instructions say.

“Hosts should use the lowest IPv4 address in the subnet, with the same tiebreaker concept as stated in #2” I assumed lowest was .1 instead of .62 for example

SO for instance, I answered this one as below.

R1 F0/0 –

What did I miss?

Reply to  Jon
January 2, 2017 10:56 am

Hi Jon,
I think it’s a terminology issue, not an addressing issue. So:
Item 2: routers… highest IP addresses
Item 4: hosts… lowest IP addresses

“hosts” being things like PCs and servers (aka not networking deices), and routers of course being routers. So the address you chose would be correct for PC1, but not for R1’s interface to that same subnet.
That do it?

Reply to  lyjo
January 2, 2017 1:48 pm

Got it. Thank you.

Reply to  lyjo
June 6, 2023 4:38 am

hello , im having the same problem .
so you are saying that we are seeing the interface from routers side(routers point of view) so we choose the highest ip address in the subnet (for that interface say f0/0),but if we were to choose from pcs/ host (point of view)we choose the lowest ip address??
thats y we choose .62 for f0/0 as we are seeing that interface from a router .
but if we were to choose from host side the ip address wouldve been .1
Please correct if i am wrong .

Wendell Odom
Reply to  sana
June 16, 2023 2:07 pm

Correct. Per the instructions: Routers use the highest IP addresses in each subnet, hosts use the lowest. That’s just a convention in this lab, though, so you get some subnetting practice along the way.

April 14, 2018 12:05 pm

Dear Wendell,
I have your hardcover book “Introduction to Networking” I was an instructor at ITT-Tech and still have opportunity to teach IT students from my home;however I do not have any access to the training material for the course; such as PowerPoint slides and lab guides and access to the material on the CD. do you have a repository That I might acquire such material? Also, do you know of any material that clearly explains the process data follows using the OSI model as a reference; say from the application layer down through each layer and up on the receiving end? I believe my explanations fall short. Thank You, Rhys Williams

January 11, 2019 3:43 pm

Isn’t the highest address in the any subnet unusable because it is the broadcast address? The router’s address would be broadcast -1?

Reply to  Rickey
January 21, 2019 10:32 am

Hi Rickey,
Yep! Of the numbers in a subnet, the lowest is reserved for the subnet ID, the highest is the subnet broadcast address, and the rest of the numbers (the numbers in between the subnet ID and subnet broadcast address) are usable as addresses for any interface connected to the subnet.