Score:0

Why are two IP addresses within the same subnet unable to ping each other?

be flag

I was setting up ip addresses between two devices and I noticed something odd. I feel like I am missing an important fundamental here:

Context:
Device A: 10.30.0.1/12
Device B: 10.2.0.2/12

if I set up the IP like this, then A and B cannot ping each other

However, if I do
Device A: 10.30.0.1/12
Device B: 10.30.0.2/12
OR
Device A: 10.2.0.1/12
Device B: 10.2.0.2/12

Then A and B can ping each other just fine. My understanding is that with a /12 netmask, the wildcard mask is 0.15.255.255, therefore the 2nd octet can be any value between 0 through 127.

Are there two groups of valid IPs being created here or is it a whitelist?

Score:1
pe flag

Device A: 10.30.0.1/12

Device B: 10.2.0.2/12

A and B are in different subnetwork.

For A

Network: 10.16.0.0

Host Min: 10.16.0.1

Host Max: 10.31.255.254

For B

Network: 10.0.0.0

Host Min: 10.0.0.1

Host Max: 10.15.255.254

As you can se both are different networks.

I left this reference IP Addressing and Subnetting for New Users, this reference will help you identify the difference between Network Mask and Wildcard

  • A network mask helps you know which portion of the address identifies the network and which portion of the address identifies the node.

  • A wildcard mask is a mask of bits that indicates which parts of an IP address are available for examination.

DSdavidDS avatar
be flag
Thanks a lot! Sample Exercise 1 was fantastic in explaining how to determine if an IP is in the same subnet and was exactly what I was looking for.
mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.