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Small IPv4 Address Guide (291,293, CCNA)

wedge1988wedge1988 Member Posts: 434 ■■■□□□□□□□
Hi guys, ive created this small txt file that ive used for revision, im posting it here because you might find it useful!



Use this table for reference, remember there are 32 bits in an IPv4 IP Address!


/0 = 0 ( 00000000.00000000.00000000.00000000 ) or 0.0.0.0
/1 = 128 ( 10000000.00000000.00000000.00000000 ) or 128.0.0.0
/2 = 192 ( 11000000.00000000.00000000.00000000 ) or 192.0.0.0
/3 = 224 ( 11100000.00000000.00000000.00000000 ) or 224.0.0.0
/4 = 240 ( 11110000.00000000.00000000.00000000 ) or 240.0.0.0
/5 = 248 ( 11111000.00000000.00000000.00000000 ) or 248.0.0.0
/6 = 252 ( 11111100.00000000.00000000.00000000 ) or 252.0.0.0
/7 = 254 ( 11111110.00000000.00000000.00000000 ) or 254.0.0.0

/8 = 0 ( 11111111.00000000.00000000.00000000 ) or 255.0.0.0
/9 = 128 ( 11111111.10000000.00000000.00000000 ) or 255.128.0.0
/10 = 192 ( 11111111.11000000.00000000.00000000 ) or 255.192.0.0
/11 = 224 ( 11111111.11100000.00000000.00000000 ) or 255.224.0.0
/12 = 240 ( 11111111.11110000.00000000.00000000 ) or 255.240.0.0
/13 = 248 ( 11111111.11111000.00000000.00000000 ) or 255.248.0.0
/14 = 252 ( 11111111.11111100.00000000.00000000 ) or 255.252.0.0
/15 = 254 ( 11111111.11111110.00000000.00000000 ) or 255.254.0.0

/16 = 0 ( 11111111.11111111.00000000.00000000 ) or 255.255.0.0
/17 = 128 ( 11111111.11111111.10000000.00000000 ) or 255.255.128.0
/18 = 192 ( 11111111.11111111.11000000.00000000 ) or 255.255.192.0
/19 = 224 ( 11111111.11111111.11100000.00000000 ) or 255.255.224.0
/20 = 240 ( 11111111.11111111.11110000.00000000 ) or 255.255.240.0
/21 = 248 ( 11111111.11111111.11111000.00000000 ) or 255.255.248.0
/22 = 252 ( 11111111.11111111.11111100.00000000 ) or 255.255.252.0
/23 = 254 ( 11111111.11111111.11111110.00000000 ) or 255.255.254.0
/24 = 255 ( 11111111.11111111.11111111.00000000 ) or 255.255.255.0

/25 = 128 ( 11111111.11111111.11111111.10000000 ) or 255.255.255.128
/26 = 192 ( 11111111.11111111.11111111.11000000 ) or 255.255.255.192
/27 = 224 ( 11111111.11111111.11111111.11100000 ) or 255.255.255.224
/28 = 240 ( 11111111.11111111.11111111.11110000 ) or 255.255.255.240
/29 = 248 ( 11111111.11111111.11111111.11111000 ) or 255.255.255.248
/30 = 252 ( 11111111.11111111.11111111.11111100 ) or 255.255.255.252
/31 = 254 ( 11111111.11111111.11111111.11111110 ) or 255.255.255.254
/32 = 255 ( 11111111.11111111.11111111.11111111 ) or 255.255.255.255




Examples: (Follow them to calculate your own for practice)



Rules:

1. there are a total of 256 addresses per octet

2. you don't have to subtract two when determining subnets (except for a few specific cases)

3. You cannot use all 1's and all 0's for IP Addresses (e.g. - 256-2 = 254)

an example: 255.255.0.0 (take 2 addresses away so 256 x 256 -2 = 65534

4. In a subnet, only one octet may carry a custom number, all others must
be either 255 or 0



Standard Example IPv4 Examples:


(Class A Standard) 256 x 256 x 256 -2 = 16777214 Hosts Available
(Class B Standard) 256 x 256 -2 = 65534 Hosts Available
(Class C Standard) 256 -2 = 254 Hosts Available




CIDR (Classless Inter-Domain Routing) examples:


1)

00001010.00000000.00000000.00000000 = ( 10.0.0.0 )

256 - 10 = 246
256 - 0 = 256
256 - 0 = 256
256 - 0 = 256

246 x 256 x 256 x 256 = 4127195136 - 2 = 4127195134 Hosts



2)

11111110.00000000.00000000.00000000 = ( 254.0.0.0 )

256 - 254 = 2
256 - 0 = 256
256 - 0 = 256
256 - 0 = 256

2 x 256 x 256 x 256 = 33554432 - 2 = 33554430 Hosts



3)

10000000.00000000.00000000.00000000 = ( 128.0.0.0 )

256 - 128 = 128
256 - 0 = 256
256 - 0 = 256
256 - 0 = 256

128 x 256 x 256 x 256 = 2147483648 -2 = 2147483646 Hosts





Formula:




LEGEND:


n = custom octet

v = Value after subtraction

octet = other octet in the range, carry out the same equation with octet

tHosts = Theoretical Maximum hosts

vHosts = Value of real Hosts

256 = a 0 address range (All other octets to the right of the custom octet
must be a 0 to accommodate for the IP addresses.

255 = lock out address

-2 = addresses that cannot be used because 0 is a wildcard address and 255
is the lock out address.

x = Multiply by


Examples:

n.0.0.0 (Unclassified)
255.n.0.0 (Class A Range)
255.255.n.0 (Class B Range)
255.255.255.n (Class C Range)


Examples:


256 - n = v
octet
octet
octet

n x octet x octet x octet = tHosts -2 = vHosts





Hope this guide was useful! ~ Wedge 1988 ~


~ wedge1988 ~ IdioT Certified~
MCSE:2003 ~ MCITP:EA ~ CCNP:R&S ~ CCNA:R&S ~ CCNA:Voice ~ Office 2000 MASTER ~ A+ ~ N+ ~ C&G:IT Diploma ~ Ofqual Entry Japanese

Comments

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    SlowhandSlowhand Mod Posts: 5,161 Mod
    That's pretty cool. There have been quite a few guides like this one out there, but very few as well-organized, laid out, and that have as much info. Great job.

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    Tyrant1919Tyrant1919 Member Posts: 519 ■■■□□□□□□□
    Ditto.

    I'd suggest just spacing some of your subnet masks in your first table so it looks all nice and pretty.
    A+/N+/S+/L+/Svr+
    MCSA:03/08/12/16 MCSE:03s/EA08/Core Infra
    CCNA
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    dynamikdynamik Banned Posts: 12,312 ■■■■■■■■■□
    Nice job.

    For rule 2, remember that you don't have to subtract two when determining subnets (except for a few specific cases).

    For rule 3, I think you mean the other values can be 255 or 0.
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    wedge1988wedge1988 Member Posts: 434 ■■■□□□□□□□
    Thanks for the promising replies guys!

    @ dynamik: Thanks dude, obviously missed that when i reviewed it!
    ~ wedge1988 ~ IdioT Certified~
    MCSE:2003 ~ MCITP:EA ~ CCNP:R&S ~ CCNA:R&S ~ CCNA:Voice ~ Office 2000 MASTER ~ A+ ~ N+ ~ C&G:IT Diploma ~ Ofqual Entry Japanese
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