Exam N10-007 All Questions

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Exam N10-007 topic 1 question 159 discussion

Actual exam question from CompTIA's N10-007

Question #: 159
Topic #: 1

Multiple users are reporting that they are unable to access the network. The ENTIRE network is shown in the diagram. PCs are not statically assigned IP addresses. The following devices will display settings:
✑ WorkstationA
✑ WorkstationB
✑ WorkstationC
✑ WorkstationD

WorkstationE -

✑ WorkstationF
✑ WorkstationG
✑ Laptop1
✑ Laptop2
✑ DHCP server1
✑ DHCP server2
Instructions:
Review the settings and select the box in the diagram that identifies the device causing the issue. Only one device can be selected at a time.
After checking the device that is causing the issue, select the second tab in the lower left hand corner. Identify the reason as to why some users are unable to access the network.
When the simulation is complete, select the Done button to submit.

Part 1 -

Part 2 -
Identify the reason as to why some users are unable to access the network.

A. Workstation(s) are plugged into switch ports configured with half duplex.
B. The site-to-site router was configured with the incorrect ACL.
C. The DHCP server scope is full and is not providing IP addresses.
D. WAN and LAN ports are reversed on the router.
E. STP has disabled some of the ports on the switch.
F. The NIC driver is not installed.
G. A wireless client is unable to associate to the AP.

Show Suggested Answer

Suggested Answer: G 🗳️

by Estiva at Nov. 13, 2019, 6:15 a.m.

Comments

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AnotherFatITGuy

Highly Voted 4 years, 3 months ago

Question states that multiple devices are having issues with network connectivity: Workstation C will never communicate properly because it will always have the APIPA address. DHCP client on the main network to the left of Router B now have 2 DHCP servers handing out different scope ip configs that will result in occasional loss of connectivity for multiple client devices. 30 years of IT experience. Last 10 years teaching around 50 classes/yr regarding networking and cybersecurity. Slowly but surely vetting all these questions for correctness. Only up through the first 200. Hope that this helps!

upvoted 22 times

netw0rk_ou

3 years, 11 months ago

i see why this is right but is that the only problem in this network

upvoted 1 times

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johnbrooks

3 years, 8 months ago

The only problem I see with your answer AFitGuy is you are 'assuming' the routers are giving out DHCP addresses. What basis do you have? If you have a DHCP server, you don't have a router doing this as well. Secondly none of the answers hint at DHCP clashes, just DHCP addy's running out, so sorry I have to disagree with your answer. BTW I don't like "G" answer either as it says 'multiple devices' which one would think it being a switch issue. So E would be the only logical one as these are two sites, ie: Internet? They don't give the far side IPs of the routers (like you said, correctness is an issue).

upvoted 1 times

johnbrooks

3 years, 8 months ago

To add to my comment, Laptop 1 got its IP from Server 2 via WAP2 and SwitchD and Server2 so that's not a problem with "A wireless client is unable to associate to the AP" Laptop1 gets its IP from Server 2 and Laptop 2 gets its IP from Server1. Tricky image are you'd think Laptop 1 belongs to Server 1, and Laptop2 belongs to Server2...

upvoted 1 times

johnbrooks

3 years, 8 months ago

and one more point to prove my point it is the STP on the switches doing the problem. The question says "Multiple users are reporting that they are unable to access the network." so even with multiple DHCP scopes, the users would still get an IP, even if "duplicate IP found on network" error shows it means connections are happening, but the question says they unable to access the network.

upvoted 2 times

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Teri0010

3 years, 5 months ago

So is it G still or C

upvoted 1 times

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[Removed]

Highly Voted 4 years, 11 months ago

Which is the wireless client that can’t access the AP please?

upvoted 11 times

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FN211

Most Recent 3 years, 3 months ago

My take is that Site A/ Workstation C is not getting an IP because SOHO router 1's connection is being blocked by STP on Switch B. Part 1 answer = Tick SOHO router 1 Part 2 answer = E. STP has disabled some of the ports on the switch.

upvoted 1 times

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johnbrooks

3 years, 8 months ago

The answer also could be the simplest - ACL issues or #B. Question says multiple users are unable to access the network, which might mean they have proper IP address, but can't connect to the other site, or network due to ACL's.

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johnbrooks

3 years, 8 months ago

My answer would be E that "STP had disabled some of the ports on the switch" to affect "multiple users". The network diagram is fine (except WStn C) as the wireless laptops are getting the proper IP from the DHCP's. Laptop2 gets its IP from Server1 (172.30.0.x) and Laptop1 gets its IP from Server2 (172.16.0.x).

upvoted 1 times

johnbrooks

3 years, 8 months ago

after long thought, it isn't STP on the switch, disregard my post. Just the idea of multiple users is throwing me. However is SOHO1 is giving out IP's because it has the WAN/LAN mixed up, it could be broadcasting out 172.30.10.x IPs to WSA, B, and Laptop2 and cause conflicts to DHCP1 (172.30.0.x) until they renew?

upvoted 1 times

johnbrooks

3 years, 8 months ago

another thought - could it be the WAN/LAN ports are reversed on Router A or B? But the question doesn't give the far side IPs of the routers for some stupid reason.

upvoted 1 times

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LeadBasedPaint

3 years, 9 months ago

I found a helpful explanation of this problem here: https://wyzguyscybersecurity.com/reference-desk/network-n10-007-performance-based-questions-pbq/

upvoted 8 times

johnbrooks

3 years, 8 months ago

I don't agree (albeit thanks to whoever did drew it out) as the wireless devices do have the proper IP address associated with the DHCP server they are getting it from. As in Laptop 2 has 172.30.0.12 from DHCP1 (scope:172.30.0.10-250) and Laptop 1 gets its IP (172.16.0.220) from DHCP2 (scope 172.16.0.10-250)

upvoted 1 times

johnbrooks

3 years, 8 months ago

sorry i keep adding, but yes the SOHO Router1 isn't giving out DHCP so WorkstationC gets an APIPA, but that's not answering the point about multiple users not connecting, just one.

upvoted 2 times

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Halaa

3 years, 4 months ago

Thanks

upvoted 1 times

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LeadBasedPaint

3 years, 9 months ago

Somewhere, there is a wireless client that is unable to associate to the AP. This lack of association is causing multiple clients to have connectivity issues. (1) Which wireless client isn't connecting to the AP and (2) how is that issue causing problems for "multiple clients"? I don't understand the answer. I don't understand how to answer Part 1 either.

upvoted 2 times

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Matt72

3 years, 11 months ago

I had 5 PBQs and thank God this wasn't one of them.

upvoted 5 times

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rose_y

3 years, 11 months ago

Long story short, workstation C is the problem.

upvoted 1 times

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Abrasive123

4 years ago

Can anyone explain for the part 1, what is the correct answer?

upvoted 1 times

johnbrooks

3 years, 8 months ago

SOHO Router1 isn't giving out IP addresses, so WSC comes up with APIPA 169.254.x.x so that is the one answer to the question. The other is maybe the WAN link on SOHO Router 1 is backwards (explains why WS-C isn't getting an IP), but doesn't explain multiple users having issues. So the other option is ACL or STP issue on Site A switch.

upvoted 1 times

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AnotherFatITGuy

4 years, 3 months ago

The network to the left of Soho Router 1 should be getting a similar addressing scheme like Soho Router 2 smaller network with a "10" being the 3rd octet. Soho Router 1's assigned address we can see is 172.30.10.1/24 and it is connected to the larger network segment. This interface should be connected to the subnet that Workstation C is on. This is the LAN interface that should hosting Workstation C's subnet and providing DHCP services there as well. Workstation C would then have a valid network address. Currently, the WAN interface, with a static ip config and NO DHCP services, is connected to Workstation C's network.

upvoted 3 times

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AnotherFatITGuy

4 years, 3 months ago

So all the addresses except for Workstation G and F in Site B are receiving an ip address from DHCP Server 2 scope of 172.16.0.0/24. Workstations G and F are getting their ip address from SOHO Router 2's DHCP scope of 172.16.10.0/24 on the LAN side of that router. Look at the ip addressing scheme: Every device connected to Router A's righthand interface has the first three octets of 172.16.0, and the network connected to the top interface of SOHO Router 2 has ips like this 172.16.10. Site A was designed to use the same ip addressing scheme. The network on the lefthand-side of Router B is being assigned ip addresses from DHCP Server 1 with a scope of 172.30.0.0/24. That main network has the 3rd octet set to "0" just like Site B's main network.

upvoted 3 times

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AnotherFatITGuy

4 years, 3 months ago

Take a look at all the devices hanging off the righthand -side of Router A in Site B. They all have ip address configs served up from DHCP Server 2 scope, because they are all connected to that subnet to the right of Router A. Ignore the line going down to Workstation D, it is a wireless client and would be connecting to the same subnet through WAP2 and Switch D. The ip address on DHCP Server 2 is a typo. I have an older screenshot of this question and the correct ip address is 172.16.0.5.

upvoted 6 times

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AnotherFatITGuy

4 years, 3 months ago

The idea was to use SOHO Router 1 in Site A just like they used SOHO Router 2 in Site B. SOHO routers can provide DHCP addresses to their LAN interface network only. The WAN interface could set to be a DHCP client if we were connecting to an ISP. But all these router interfaces are connected to internal subnets, except for the blue WAN link between Router B and Router A. The diagram doesn't even give us ip addressing info for that link. In this case, both SOHO Routers' LAN and WAN interface's ip addresses and masks would be statically configured with the LAN interface providing DHCP service to the LAN side only.

upvoted 6 times

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AnotherFatITGuy

4 years, 3 months ago

The secret to this question is why does Workstation C have APIPA (169.254.200.67). SOHO Router 1 has its interfaces plugged into the wrong network segments. The correct answer is SOHO Router 1 should be checked in Part 1, and "D" The WAN/LAN ports are reversed on the router should be selected in Part 2.

upvoted 10 times

johnbrooks

3 years, 8 months ago

I think you have the right answer! Nothing else seems to work. It wouldn't be a driver issue for the WS as it got an IP even if 169.254, and all the wireless devices have the right IP addresses to the DHCP server it is connected to.

upvoted 1 times

johnbrooks

3 years, 8 months ago

only problem with the SOHO router is the question being multiple users with the problem, WS-C is the only one affected. However, SOHO1 can't see anyone else due to its IP being 172.30.10.1 and everyone else is 172.30.0.x,

upvoted 2 times

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heff

4 years, 4 months ago

Another terrible question from CompTia. Assuming Part A and Part B are related (a stretch for CompTia I know) i.e. checkmark the problem device then identify the reason. Workstation C has an APIPA address which is the symtom of the problem. What can cause this; IP not refreshed, Ethernet cable damaged, Nic goes down, DHCP server issues. Many many reasons. Therefore we must look to part 2 for the possible answers and start eliminating. C or F are most likely to be consistent with APIPA. C is not the issue as there are no issue with available addresses in the scope. So it must be F - Nic driver is not installed. My answer = Workstation C, NIC driver not installed. Caveat Issue is presenting in Site A. DHCP Server 2 does have incorrect gateway (typo possibly) but no issues are presenting in Site B

upvoted 3 times

johnbrooks

3 years, 8 months ago

I have to disagree with the NIC driver issue, if this was the case then APIPA wouldn't work. APIPA works when the computer can't get an IP from a DHCP service, so it will self assign one and thereby be able to talk to others on the same network, meaning the driver is working.

upvoted 2 times

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Drchattss

4 years, 4 months ago

This was my question ONE today, had NO idea, even the other two were just as bad so back to drawing board

upvoted 2 times

Alfall

4 years ago

Do you remember the other 2?

upvoted 1 times

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