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New Member

subnets

If I have a ip of 172.19.51.0/24 is this all a subnet of the 172 and 172.19 network ?

6 REPLIES
Silver

Re: subnets

Hi Carl,

Since the mask is /24 ie)255.255.255.0, first three octet is a network portion.

172.19.51.0 is a network with 255 hosts. It is came from by subneting the network 172.19.0.0.

Rgs.

New Member

Re: subnets

I still dont understand why its a subnet of the 172.19 network, so would say 185.100.34.0/24 be a subnet of the 185.100 network ?

Cisco Employee

Re: subnets

Absolutely. 185.100.0.0 is a class B and 185.100.34.0/24 is its subnet.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Cisco Employee

Re: subnets

If you go based on the classful model then 172 is a class B and your major net is 172.19/16.

With the classless model you only rely on the prefix and prefix length and you could say that 172.19.51.0/24 is a more specific prefix of both 172/8 and 172.19/16.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: subnets

first off: 172.0.0.0 is one of the reserved ip addresses....10.- 127.- 172 - 192 are the reserved ip addresses made by the IETF..

Cisco Employee

Re: subnets

You probably meant that it is part of the private address space defined by RFC1918 as follow:

10.0.0.0/8 (10.0.0.0 - 10.255.255.255)

172.16.0.0/12 (172.16.0.0 - 172.31.255.255)

192.168.0.0/16 (192.168.0.0 - 192.168.255.255)

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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