r/firealarms • u/Mln3d • 3d ago

Discussion Test Question

I had a test question that I can’t remember verbatim.

Effectively it was asking what was the subnet it static ip when having a fire alarm connected up to a router.

It was like:

255.0.0.0
255.255.0.0
255.255.255.0
255.255.255.255

192.168.0.0
192.168.1.0
192.168.0.1
192.168.1.1

Other part was if it’s attaching a releasing panel to a buildings router what is the router address to be offered to IT?

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u/Acrobatic_Entry1645 3d ago

So the question as you stated is a little confusing because unless this is on equipment has a set manufacturer suggestion, we would need to know a list of IP addresses you are trying to use to figure out the subnet mask. If that is what the second set if address are supposed to be then the subnet mask should be 255.255.0.0

I don't feel like there is enough info to figure out the the IP of the router. I also feel like you wouldnt be telling IT the IP address of the router. Wouldn't they be telling you that?

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u/Mln3d 3d ago

That was my thought that it was extremely vague. Supposedly the question was derived from Networking for Dummies.

But this is the only relevant thing I can find in there but their is no relation to fire alarm more or less just “private”

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u/Mln3d 3d ago

My thought is the 255.255.0.0 and the. The 192.168.0.1 would be the correct answers

1

u/Acrobatic_Entry1645 3d ago

That would be a good guess. 192.168.0.1 is a fairly common address for a router. However, equally common in that same subnet would be 192.168.1.1 and 192.168.1.100. All the address listed are possible to set as a router address though. Just some make more sense in a real world scenario where you want addresses to make sense.

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u/Mln3d 3d ago

Yeah that’s what’s a bit confusing. It seems like a horridly designed question.

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u/Starlite528 3d ago

it's 255.255.255.0. It's always that, lol.

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u/Mln3d 3d ago

Can’t find that on private address in the book for reference.

1

u/Starlite528 1d ago

That's based on my experience rather than book theory. I've had my hands on hundreds if not thousands of networks, and 98% of the time it's /24.

1

u/Mln3d 1d ago

Weird, it doesn’t really give 255.255.255.0 seems err on the 255.255.0.0

1

u/Starlite528 1d ago

Sounds like a poorly written or intentionally confusing question. 192.168.0.0 and 192.168.1.0 will be a non-assignable address labelled as the 'network address' in 99% of scenarios. There is a way to use it but the subnet mask would be 255.255.255.254 and it's meant for a point to point link where the only other ip is the dot1.

The other two IP address examples can fit within any of the first three subnet masks. A 'router address' will be the 'default gateway' and that can be any address within the subnet, but is usually dot1 or dot254.

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u/Mln3d 1d ago

This is what I could find In the book it referenced 255.255.0.0 - 192.168.0.1-192.168.255.254