Urgent Questions about subnetting

ExamHelpMe

Question 1:

Given a Network of 172.16.0.0 /16

You want to divide the network into subnets.

You will allow at least 600 nodes per subnet, what is the subnet size? (26??)

What subnet mask should you use? (255.255.255.192 /26)

What are the first 2 subnets

What is the address of the first node on the first subnet?

What address would this node use to send to all devices on its subnet?

Showing your work would be great i do not understand full how to answer some of these questions i put some answers in brackets to the ones i feel like i got the answer for thanks in advance!!!

clarson

You will allow at least 600 nodes per subnet, what is the subnet size? (26??)

nodes = hosts you need enough hosts bits for a number greater than 600.
8 bits = 256, not enough. add one more host bit, multiply x 2. 9 bits = 512, still not enough
add one more bit, multiply x 2. 10 bits = 1024 that is enough.
10 host bits. 32 bit in ipv4 network address. subtract the 10 hosts bits = 22 network bits. /22

ExamHelpMe

thanks for clearing that up that nodes = hosts !!!

If its not too much to ask could you answer my other questions aswell?

clarson

What subnet mask should you use? (255.255.255.192 /26)

/22 255.255. 11111100 . 0

you can add all those ones up. 128+64+32+16+8+4 = 252

subtract the 2 zero bits 11 binary is 3 decimal, add 1 give a block size of 4, 256 -4 = 252
or remember a point to point network is a /30 255.255.255. 11111100
and a /30 network is 255.255.255.252 so 11111100 is 252

subnet mast is 255.255.252.0

ExamHelpMe

thanks thats what i got aswell but im not sure what the following questions want me to figure out...

1) What are the first 2 subnets?

2) What is the address of the first node on the first subnet?

3) What address would this node use to send to all devices on its subnet?

with the information given above

if you could do these questions for me it would be awesome!!!

clarson

What are the first 2 subnets

network address is 172.16.0.0
first subnet has subnet bits all zero and host bits all zero, 172.16.0.0
2nd subnet has the first (right most) subnet bit set to 1.
nnnn nnnn.nnnn nnnn.ssss sshh.hhhh hhhh
172.16. 0000 0100.0000 0000
172.16.4.0 is the 2nd subnet

or from previous question block size is 4. so add 4 to the 3rd octet 172.16.4.0

clarson

What is the address of the first node on the first subnet?
first subnet has all subnet bit set to zero and all host bits set to zero
first host set the rightmost host bit to 1

nnnn nnnn.nnnn nnnn.ssss sshh.hhhh hhhh

172.16. 0000 0000.0000 0001
172.16.0.1

clarson

3) What address would this node use to send to all devices on its subnet?

you use the broadcast address to send to all devices on a subnet
it is on the first subnet so all subnet bits set to 0
the broadcast address has all the hosts bit set to 1

nnnn nnnn.nnnn nnnn.ssss sshh.hhhh hhhh

172.16. 0000 0011.1111 1111
172.16.3.255

ExamHelpMe

Thanks ALOT!! you taught me better than my prof did haha

ExamHelpMe

Hey sorry to bug you again but what would change if it was

4) What is the address of the last node on the last subnet?

clarson

4) What is the address of the last node on the last subnet?

last subnet all subnet bits set to 1
all the host bits set to 1 but that is the broadcast address so the last host is
all the host bits set to 1 but the last or right most one is set to 0

nnnn nnnn.nnnn nnnn.ssss sshh.hhhh hhhh

172.16.1111 1111.1111 1110
172.16.255.254

ExamHelpMe

so you said that all the host bits are set to 1 but the last one or the right most one is set to 0 but you set the subnet to 1s aswell?

clarson

last subnet all subnet bits set to 1 <

---

all the host bits set to 1 but that is the broadcast address so the last host is
all the host bits set to 1 but the last or right most one is set to 0

ExamHelpMe

thanks for the help again!

pinkiaiii

you def need invest time into getting around subnetting since it not even a trick question or difficult to answer.

personally i would just counted from 64k+ subnets so if you know that class b has 64 thousand then taking one bit makes it
32k,16k,8k,4k,2k,1k
magic number 4 bits used 6 means 64 subnets.
very first ip is always 1 if starting with network address.
now havent dont subneting in long time so only slip up to watch not to use network address as last like 4.255
and that said br address is usually 255 as well just depents on the octet's and class of ip.

simple practice question you could try if hosts needed is 1000 with ip 192.168.0.0 /24 now that's superneting but if you can learn to do that both ways and answer same questions you will master it easily.Now finding hosts number is easy task its harder to calculate subnet total amount in such scenario,but still possible to do count on fingers if needed.