Ping responses from devices that don't exist

[adel85]

hello

recently I added new 2 network range in my company and haven't used more than 8 IP from both ranges

problem is, I did IP scan from a machine and found more than 45 IP from those ranges are taken and ping-able even though I am not using those

I tried to trace any of them but it time out, only ping reply

I tried to look into VPN, company entire network but nothing exist in those range except when I created them and used 8 only IP

i looked into ARP table and cleared the ARP-cache, still didn't solve it. 

[Asemmoqbel]

Hi,

Where these two network are teminated? and do you enable dhcp for these networks?

To definitely make sure if these IPs are live on your network, you can trace these IPs untill you know where exactly they are connected by using Mac address from arp table.

[adel85]

my DHCP is 10 network, 

the new network ranges i added recently and only used 8 IP are: 172.16.34.0 & 172.16.33.0

if you read my post i mentioned i can ping and get reply but trace is timing out

[Asemmoqbel]

we eliminate the possibility that a DHCP may distribute these IPs.

when you trace you get reply timed out because you are on same network.

You can trace these IPs using mac address as following:

1- From the switch type: "" show arp"".

2- you will find arp entries for these IPs with mac address.

3- first check, do they all have different mac address? then choose one random IP and copy its mac-address.

4- from the same switch type ""show mac address-table | inc <xxxx.xxxx.xxxx>

then from the output you will see the interface which the switch receives this mac-address from. if the interface is connected to a pc or server, physically go check that device.

and if the interface is connected to another switch, you need to access that switch and type the previous command ""show mac address-table | inc <xxxx.xxxx.xxxx>.

keep tracing this mac address until you find where exactly it's connected to.

[adel85]

thx for replying , before posting,I have already did that but arp doesnt show these network 

only managed to find post on different site with similar issue longtime ago but he didnt resolve it 

Ping responses from devices that don't exist - Networking - Spiceworks

[Asemmoqbel]

"" i looked into ARP table and cleared the ARP-cache, still didn't solve it ""

I thought when said the above statement in your first post that you can see ARP entries for theses IPs. 

In this case, from where you are pinging these IPs? from the machine or switch and since the Ping succeed, indeed there will be arp entry because without mac address ping will Fail!!