Can someone explain the correct answer to this question please?

After building a small network and connecting it to your ISP you notice that the clients are unable to browse the Internet. You call your ISP and he asks for the information configured on your router. You present the required information to him. He says the information is as it should be. You browse the net from the computer directly connected to your DSL modem and you are able to do so. What could the problem be?
A. Incorrect IP configuration
B. DNS not configured on the workstations
C. DNS server not set on the DHCP server
D. Default gateway not set on the workstations

It seems like 3 of the answers could be correct, but only one is. I do not understand how you could pick out one of them as definitely being the right one.

Yea, it looks like more than one could be the case.

You sure it's not multiple answer?

The system only accepts one answer, which I already got wrong.

which was wrong?

It's D. But why not A or B? The only reason it can't be C is because I'm trusting the guy from my ISP O_O

yea, it's a vague and ambiguous question....

So there is just no reasoning behind it at all? I'm not just missing something obvious?


1 Like

The question is crap.

But assuming a normal routers function and the PC is using the routers dhcp then a,b,d are wrong because they are all provided by dhcp, meaning the answer is c and the ISP customer support lives up to standards and can't be trusted.

Could be b, but it says only the internet doesn't work.. So.. B or c xD

1 Like

What I am curious is, which system asked this question and only accepted one answer?
Is that a question from some sort of networking course?

A incorrect ip configuration would not even allow you to connect

DNS just resolves names from to XXX.XXX.XXX.XXX

Default gateway tells the computer where to connect to the internet

1 Like

It says the answer is D. It is a practice test for Network+. It must have just been made by some random dude on the internet, who doesn't know what he's doing. But I failed the real exam a couple days ago and it seemed like there were a lot of questions like this. It's like there is some secret list of bullshit "correct" answers that you basically just have to guess because there is no way to narrow it down. Seeing a lot of these questions starts to make me think I am idiot or something. I feel better now.

I am asking because

is usually caused by a missconfigured DHCP ... many consumer routers do it automatically and set the standard gateway to their LAN address so consumers do not see this "complicated nonsens";

Ok, if these are the questions the + isn't worth it ... imo

They want to train you to do telefone troubleshooting.. ya know.. client calling "my e-mail is not working" - "ok what program do you use" - "i don't use a program" - "how do you get to your mail" - "internet explorer" - ....... that's where such dumb failure descriptions origin from.

1 Like

It's actually a requirement for a job that will pay me more than twice what I make now. They said I could also retake the A+, but that's two tests vs. one. I only failed by one or two questions so might as well retake it. Otherwise, yes it's completely worthless.

1 Like

If anybody here is going to take CompTia certs, be prepared for questions like these. Their tests are filled with ambiguous questions.

The secret to this question is where they say

This means it could not be B or C.

This is a giveaway to the correct answer D because they have no gateway to tell them where to go, your ISP and testing already verified that your router information is correct.

This also is where they get you with tricky wording, it eliminates A because they would have said the computers cannot browse the internet or intranet, that would indicate an incorrect IP or DHCP configuration.


This is exactly the answer I was looking for. It's a logic problem basically. Of course you have to know what the answers mean to understand the logic, but I wasn't recognizing that one bit of information that justifies it one way or the other.

Essentially I have to assume that all the workstations are configured the same as the one plugged into the modem, which didn't occur to me.

The trick part of the question is this. Because it says they verified the router information is correct, which it isn't because it isn't giving out the gateway with DHCP.

Argh I forgot about this. That's why I didn't pick D... I shall now return to my previous state of disillusionment.

That's assuming you are using DHCP and not static.

Which is a fair assumption to make in 2016; I usually assume that DHCP is used, until I find out different.