Stuck on Subnetting

[us3rnotfound]

I understood subnetting A and B networks, but I don't quite get one aspect about class C networks. The Subnet ID goes in the beginning of the 4th octet, so where is the host portion designated if that's the final octet? 😕

For example, the network 192.168.1.0 with a Subnet Mask of 255.255.255.224. That would make the first available subnet 192.168.1.32. So, where is the host in this 32-bit IP Address?

 

[nightowl]

The host space for the network 192.168.1.32 will be .33 through .62. Your broadcast address would be 192.168.1.63 and you have a new network every increment of 32 (32,64,96,128,..., 224).

 

[Goosemaster]

I hate to sound like an old fogie, but try looking at it in binary..it makes it so much easier...

 

[spidey07]

Originally posted by: us3rnotfound
I understood subnetting A and B networks, but I don't quite get one aspect about class C networks. The Subnet ID goes in the beginning of the 4th octet, so where is the host portion designated if that's the final octet? 😕

For example, the network 192.168.1.0 with a Subnet Mask of 255.255.255.224. That would make the first available subnet 192.168.1.32. So, where is the host in this 32-bit IP Address?

arrgggg.....are they STILL teaching that the zero subnet is not usable. Please flog whoever is teaching you this.
*sigh*

Do the binary. 256-224 = 32. your subnets are in blocks of 32.
.0
.32
.64
.96
.128

etc.

first and last number on those is the network and broadcast address.
.32 is net
.33 is first host
.62 is last host
.63 is broadcast.

 

[nightowl]

I questioned weather I should mention the zero subnet but I opted to not mention it for the sake of not creating more confusion.

 

[spidey07]

Originally posted by: nightowl
I questioned weather I should mention the zero subnet but I opted to not mention it for the sake of not creating more confusion.

If you're in an educational/training situation, just leave it be.

 

[nweaver]

I would second the binary thing, it all started coming together when I got it on that level.

 

[us3rnotfound]

Originally posted by: Goosemaster
I hate to sound like an old fogie, but try looking at it in binary..it makes it so much easier...

Yeah, I'm finding that's the best way

 

[Tarrant64]

Originally posted by: spidey07

Originally posted by: us3rnotfound
I understood subnetting A and B networks, but I don't quite get one aspect about class C networks. The Subnet ID goes in the beginning of the 4th octet, so where is the host portion designated if that's the final octet? 😕

For example, the network 192.168.1.0 with a Subnet Mask of 255.255.255.224. That would make the first available subnet 192.168.1.32. So, where is the host in this 32-bit IP Address?

arrgggg.....are they STILL teaching that the zero subnet is not usable. Please flog whoever is teaching you this.
*sigh*

Do the binary. 256-224 = 32. your subnets are in blocks of 32.
.0
.32
.64
.96
.128

etc.

first and last number on those is the network and broadcast address.
.32 is net
.33 is first host
.62 is last host
.63 is broadcast.

Holy cow that just put a lot of stuff about networking together for me. I took cisco in high school and they totally messed it up while teaching us. I usually had someone help me when it came to subnetting, but that post right there cleared it all up.


wow....

just..wow.

 

[spidey07]

Tarrant,

When you've been doing it for a while you literally do it all in your head. I still count binary on my fingers...

hmm, 20 bit mask...

128 (1 finger)
192 (2 finger)
224 (3)
240 (4)

so a 20 bit mask is 255.255.240.0.

256 - 240 = 16. So nets are 0, 16, 32, 48, etc

That's the "easy" way. You just have to remember to count..
128
192
224
240
248
252
254


It also helps to use prefix notation as a habit. (10.202.224.0/19) It will force you to think in terms of how many bits are in the mask.