Internship Interview Take-Home Problem (simple, but I'm new!)

[SweetTechieKate]

Hey guys! My name is Kate. I am going back to school for a degree in CS because I hated my future career path in finance and sales.

Anyhow, I had an interview for an internship for a network security firm. My interviewer gave me a simple take home problem and I am looking for some pointers.

The problem is to manually apply an IP address and Default gateway given to me by my interviewer and come up with the subnet mask that will allow my computer to connect with the router.

I have a desktop with Windows XP and a wireless connection with a Netgear router. I am upstairs, the wireless router is downstairs.

My interviewer instructed me to go to Wireless Connection > Properties > General Tab > Internet Protocol TCP/IP > Properties > General Tab >

Then switch from "Obtain IP address automatically" to "Use the following IP address:"

Once there he instructed me to fill in:

IP address: 192.168.0.100 (not sure if that makes a difference)
Subnet Mask: (this is what I need to find out for my internet to work!)
Default Gateway: 192.168.5.1 (his arbitrary gateway to manually add)

When toying around the subnet mask would automatically fill in as 255.255.255.0 and I thought that is the right answer and it would work. It does not however. The internet connection stays connected but no more packets will be received.

What am I doing wrong?

I am new to this field, if I answer this question soon I have a shot at this internship! :laughing:

 

[C0RR0SIVE]

could always make it 255.255.0.0 not entirely sure though, as the 255.255.0.0 would allow192.168.0.0 - 192.168.254.254 ip address to communicate, which is a VERY large range...

 

[SweetTechieKate]

Tried that, no go. I also tried 255.255.255. (0,128,192,224,240,248,252).

My defaults are:
IP: 192.168.1.100
Subnet Mask: 255.255.255.0
Default gateway: 192.168.1.1

What does his changing my default gateway to 192.168.5.1 have to do with affecting my connection?

 

[D-Rocks]

Do you know what device the default gateway is used for?

Tried that, no go. I also tried 255.255.255. (0,128,192,224,240,248,252).

My defaults are:
IP: 192.168.1.100
Subnet Mask: 255.255.255.0
Default gateway: 192.168.1.1

What does his changing my default gateway to 192.168.5.1 have to do with affecting my connection?

 

[mikesgroovin]

could always make it 255.255.0.0 not entirely sure though, as the 255.255.0.0 would allow192.168.0.0 - 192.168.254.254 ip address to communicate, which is a VERY large range...

Using that subnet, It's actually 192.168.255.254 as your last host (you missed a subnet) not being a ******... sorry, just for informational purposes hehe


Simply put, the default gateway address is the address that the host uses in order to get out of your local network. It's not going to work unless you have a device at that address that is communicating with the internet.

The closest subnet range to include your host address (192.168.0.100) and your default gateway address (192.168.5.1) would be 255.255.248.0. This would encompass 192.168.0.1 all the way to 192.168.7.254 and x.x.x.255 as your broadcast. In order for 0.100 and 5.1 to communicate on the same subnet, that would have to be your mask... 255.255.255.0 wouldn't work.

 

[D-Rocks]

Well said mike

Simply put, the default gateway address is the address that the host uses in order to get out of your local network. It's not going to work unless you have a device at that address that is communicating with the internet.

The closest subnet range to include your host address (192.168.0.100) and your default gateway address (192.168.5.1) would be 255.255.248.0. This would encompass 192.168.0.1 all the way to 192.168.7.254 and x.x.x.255 as your broadcast. In order for 0.100 and 5.1 to communicate on the same subnet, that would have to be your mask... 255.255.255.0 wouldn't work.

 

[mikesgroovin]

Thanks...

It's an interesting question... not the logic of the answer thats interesting though... just the fact that it could be presented as a trick question if the interviewer was expecting 255.255.255.0 as an answer.

 

[oldskool]

Using that subnet, It's actually 192.168.255.254 as your last host (you missed a subnet) not being a ******... sorry, just for informational purposes hehe


Simply put, the default gateway address is the address that the host uses in order to get out of your local network. It's not going to work unless you have a device at that address that is communicating with the internet.

The closest subnet range to include your host address (192.168.0.100) and your default gateway address (192.168.5.1) would be 255.255.248.0. This would encompass 192.168.0.1 all the way to 192.168.7.254 and x.x.x.255 as your broadcast. In order for 0.100 and 5.1 to communicate on the same subnet, that would have to be your mask... 255.255.255.0 wouldn't work.

I have yet to not learn something reading your posts, mate !

 

[mikesgroovin]

Again thanks...
some of the more typical addressing schemes, after being in the field long enough, you will just know by heart. But, I have yet to be in a planning/problematic situation where the infrastructure/engineer didn't have a subnet calculator in order to check his/her work or figure it out in a pinch. You'd be silly not to...

 

[oldskool]

I have a software-based subnet calculator, I think its called NetCalc - on my other machine. Maybe thats not the name of it...anyway, I mess with that now and then it is helpful in learning what subnet masks will do to a Class B or Class C IP address, you know um what's the terminology ? Oh the "ANDing". Just remembered the process I was trying to think of. Cool program, I just cant remember for sure the name of that program right at this time.