Answers: IPv4 Addresses 5
By certskills
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.
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 (255.255.255.192) mask in this particular exercise.
Table 1: IPv4 Addresses
| Location | IP/mask |
| R1 F0/0 | 172.18.1.62 /26 |
| R1 S0/0/0 | 172.18.8.125 /26 |
| R1 S0/0/1 | 172.18.8.189 /26 |
| R2 F0/0 | 172.18.2.126 /26 |
| R2 S0/0/0 | 172.18.8.253 /26 |
| R2 S0/0/1 | 172.18.8.126 /26 |
| R3 F0/0 | 172.18.3.190 /26 |
| R3 S0/0/0 | 172.18.8.190 /26 |
| R3 S0/0/1 | 172.18.8.254 /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
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1 2 3 4 5 6 7 8 |
interface FastEthernet0/0 ip address 172.18.1.62 255.255.255.192 ! interface Serial0/0/0 ip address 172.18.8.125 255.255.255.192 ! interface Serial0/0/1 ip address 172.18.8.189 255.255.255.192 |
Example 2: R2 IPv4 Address Configuration
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1 2 3 4 5 6 7 8 |
interface FastEthernet0/0 ip address 172.18.2.126 255.255.255.192 ! interface Serial0/0/0 ip address 172.18.8.253 255.255.255.192 ! interface Serial0/0/1 ip address 172.18.8.126 255.255.255.192 |
Example 3: R3 IPv4 Address Configuration
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1 2 3 4 5 6 7 8 |
interface FastEthernet0/0 ip address 172.18.3.190 255.255.255.192 ! interface Serial0/0/0 ip address 172.18.8.190 255.255.255.192 ! interface Serial0/0/1 ip address 172.18.8.254 255.255.255.192 |
By certskills
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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?
Bav,
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.
Wendell
Back in 2012? That’s crazy. Here I am 2020 benefiting from your work!!! I was in the 7th grade when you set the questions lol
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 172.18.1.1 not 172.18.1.62
same for R2 and R3
JP,
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.
so there are no host ip’s configured? I used the same logic as JP
Hi Jorge,
No.
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,
Wendell