CCNA Router Summarization: Speed Your Network

[edachar]

the link to the free courses takes your email address but does not link to any videos. Looks like a spam scam.

[miszczpolska]

MyWay Lets take as an example the range of IPs 172.16.128.0-172.16.159.255 We see that the network mask will have to affect 3rd octet. The easy way it to subtract 128 from 159. Lets see 159-128=31 Now subtract 31 from 255 255-31=224 There we go, this is our 3rd octet in the subnet mask 172.16.128.0 255.255.224.0 Another example Summarize networks 100.16.0.0 100.17.0.0 100.18.0.0 100.19.0.0 19-16=3 255-3=252 Our subnet mask is 255.252.0.0 for network 100.16.0.0