I'm on a LAN provided by an ISP. My computer has its IP address, Subnet Mask, Default Gateway, DNS Servers(using DHCP).
I've been teaching myself bit of networking. I just wanted to apply the concepts I learned to my LAN.
So, what I did is I've figured out all the IPs on my LAN using subnet mask and pinged all of them using a batch script. I just wanted to see the MAC addresses of all the computers on my LAN. Then I've checked my arp cache by issuing command
arp -a. I'm surprised to see the result. It was a huge list with all IP addresses (alive on my LAN) as expected but all had the same MAC address.
How did this happen? What's going on? If all nodes have the same MAC address then how will the communication work?
I still don't get it. Let me clarify what I did.
- After applying subnet mask
255.255.192.0on my IP I got:
- Which gives me 16384 IP addresses ranging from
- First and last IP addresses cannot be used as they are Network address and Broadcast address respectively.
- So, My subnet or local network contains 16382 hosts/computers. Right? In other words these 16382 hosts are behind single router.
I want to see the mac addresses of these hosts. SO, I pinged all of them and the above picture shows the result
Now if I think little bit more about it. 16382 hosts behind a single router means too much of broadcast traffic (ARP broadcast). Which is not desirable. At the same time they cannot be connected to different routers because that would mean they are on different networks. May be they are on different VLAN (I don't know much about VLAN but I just know that it helps reducing the broadcast traffic).
I don't understand what is my problem. Kindly identify what am I getting wrong?