CIDR 5

Question:
How can I get the CIDR if only IP Address given without prefix?


You cannot possibly get the subnet mask or CIDR with just having the IP address. If you KNEW for a fact that you were not subnetting, then it would be easy, because the CIDR would be /8 for a Class A, /16 for a Class B, and /24 for a Class C, but with subnetting, all bets are off.



Question :
Does 195.251.117.155/25 have a next Network ID or is completed because the multiple of 128 brought it over 255 ?

Joal Diaz - the cidr 25 shows the subnet mask at 255.255.255.128, so the first subnet would start at 195.251.117.0 and go to 195.251.117.127. The second subnet would start at 195.251.117.128 and go to 195.251.117.255 which completes the array. The broadcast addresses are 117.127 and 117.255..

Joal Diaz so that is the last subnet, because the next one would take it to 195.251.117.256, which you can't have. so that is a 2 subnet network!