AQA Computing CPT5 networking stuck!

Hello all
I'm just revising for my AQA unit 5 computing A2 exam coming up in ONE WEEK ish :eek:

(yes i'm proper worried) and it's become apparant that I am slightly bad at networking (haha slight under statement :rolleyes:

). Wondered if anyone could please please help me with this question? it's from June 06 if anyone wants to find mark scheme

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Tom’s family has asked you for some advice about networking. They have just moved to a new house, currently without any communication links. They want Internet access for the family desktop computer.

(c) Tom’s mother’s laptop computer is set up with an IP address of 192.168.28.175 and
Tom’s father’s laptop computer uses IP address 192.168.15.12.
(i) What would be a sensible IP network ID? ................................................................
(1 mark)
(ii) What is the range of IP addresses available for the family desktop computer?
....................................................................................................................................
(2 marks)
(iii) What would be the subnet mask for this network?
....................................................................................................................................
(1 mark)

Thoughts:
I thought 192 was a class C network (which is NNNH layout of an IP address. i remember that bit!). and but apparantly the answer to the first one is 192.168? or as an alternative the mark scheme gave 192.168.0.0.
And I was thinking what happened to the 3rd portion after the 168.

If anyone could please help or just give me any resources on networking in general I would be highly appreciative.

James Air

Reply 1

secretmessages

Well, if there are two computers on the network, with IPs of 192.168.28.175 and 192.168.15.12, only the 192.168 is common of both IP addresses, so a suitable network ID would be 192.168. I wouldn't suggest putting 192.168.0.0 down - it's just about correct, but not the perfect answer. If, for example, the two IPs were 192.168.28.175 and 192.168.28.176, a suitable network ID would be 192.168.28, as this is common to both addreses.

Part two, well we've already established that the network ID is 192.168, so other computers on the network can have any valid IP address that starts with 192.168 (except for 192.168.0.0, and also strictly 192.168.0.1 and 192.168.255.255 too). So this would be the range available - 192.168.0.1 to 192.168.255.254.

Hope this helps a bit. Good luck in the exam.

Reply 2

Defcon

Haven't started the A2 units yet but I believe the answer to part 3 would be 255.255.0.0 ?

Reply 3

jamesair99

thanks so much for your help secretmessages and Defcon
I've just read up on subnet masks and I agree with Defcon. My understanding of it is:

because for them to be on the same network it's gotta start like 192.168.
and so if you AND 192.168.28.175 with 255.255.0.0 you get 192.168.0.0 which is the network thingy

and the same with 192.168.15.12. if you and it with 255.255.0.0 you get the network address!

ooo oo there's a beast of a network question in the jan 08 paper as well. :frown:

Reply 4

LauraHK

I don't understand how to quickly work out the subnet mask for the exam...

sometimes it's 255.255.255.0 and sometimes 255.255.0.0

I have no AND function on my calculator and even if I did I wouldn't know how to use it...

Please help! Thanks in advance :smile:

Laura

Reply 5

jamesair99

LauraHK

Laura

it was a while since i did this now but i think it is to do with which class the network is in? like there are 4 octets and it can be Network Network Network Host or Network Network Host Host? (am i making sense?) and that can help determine whether it is 255 255 255 0 or 255 255 0 0 respectively.

as far as determining the class is concerned if i remember rightly you can either just remember the addresses or convert the IP address into binary and then beginning with 0 means its A. then 10 means B i think and then 11 means C? it's something like that you should check it! but there's a pattern and that's how you know!

Reply 6

surprise990

on a realated topic 2 minor bit I could understand from the JAN 08 CPT5 paper.

1d) for defining the ItemTaken field why do they have an '''accession number''' . I thought it would be a composite key of '''quantity''', '''teachers initials''' and '''ItemCode'''.

6bi, ii, iii)

can someone explain how they get them IP addresses.

thanks

Reply 7