Answers: IPv4 Addresses 5

By certskills September 19, 2012 09:00

Look back at the original problem statement, calculate the IP addresses to be used by routers and hosts, and create the router configuration for in the interfaces in the network diagram. Today’s post shows the answers.


Your first task was to calculate the IP addresses to use, based on requirements. For reference, Table 1 lists the results. Note that all subnets use a /26 ( mask in this particular exercise.

Table 1: IPv4 Addresses

Location IP/mask
R1 F0/0 /26
R1 S0/0/0 /26
R1 S0/0/1 /26
R2 F0/0 /26
R2 S0/0/0 /26
R2 S0/0/1 /26
R3 F0/0 /26
R3 S0/0/0 /26
R3 S0/0/1 /26


To create the configuration, all you have to do is add the ip address command to each interface in configuration mode. Easy once you’d done it a few times; here are the answers to be complete.

Example 1: R1 IPv4 Address Configuration


Example 2: R2 IPv4 Address Configuration


Example 3: R3 IPv4 Address Configuration


IPv4 Addresses 5
STP Puzzle 3
By certskills September 19, 2012 09:00
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  1. Bav July 2, 10:37

    Maybe I was reading it wrong but I don’t see how requirement 4 is actually a requirement. All the bank boxes are relating to Router interfaces, not hosts. Is that right?

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    • CCENTSkills July 5, 09:33

      I see your point. I’m sure I just copy/pasted the intro text from a similar lab – I think I made five or six of these similar labs back in 2012, and a few had hosts in them.

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  2. JP August 6, 14:22

    The host address should be the first available address on the network per #4
    4. Hosts should use the lowest IPV4 address in the subnet, with the same tiebreaker concept as stated in #2.
    R1 f0/0 should be not
    same for R2 and R3

    Reply to this comment
    • certskills Author August 10, 12:53

      My reading of the lab states that requirement #2 tells us to use the highest IP addresses in the subnets for routers, and the lowest for hosts. I think you’re applying the lab requirement #4 to both hosts and routers. So I think the suggested answer’s router IP addresses are correct per the lab requirements.

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      • jorge3687Jorge December 7, 13:14

        so there are no host ip’s configured? I used the same logic as JP

        Reply to this comment
        • Wendell Odom December 7, 16:31

          Hi Jorge,
          Choose addresses for hosts (that is, not routers) as the lowest numbers in the subnet.
          Choose addresses for routers (that is, not hosts) as the highest numbers in the subnet.
          That’s what I clarified to JP.
          Hope this helps,

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