Communication between two APIPA computers without DHCP Server

On the last Saturday Me and my friend are trying to connect two computers directly using a USB cable and start communication between these two computers without the help of any external DHCP server. As I mentioned in my previous post we cannot use ordinary USB cable to connect two computers directly. It may burn the USB port.

[ To know more about it please follow the link below. ]

In this project we avoid using router or any other DHCP servers. As we are not using the Ethernet adapters we cannot set any static IP address. So without the presence of external DHCP server and static IP address our both computers will get APIPA from Windows Operating System.

[ To know more about APIPA please click on the link below. ]

So the IP address our computers got was 169.254.X.X range. Fortunately the IP address gained by our computers were in the range 169.254.1.X and it started to communicate with each other.

It is sure that APIPA computers can communicate each other as their subnet mask is (Class B address). So as the subnet rules says the network address of APIPA is and the broadcast address is Any address comes in between these range can communicate each other. Because it is a private IP address we cannot use APIPA to get Internet connection to our computers. For Local networks and Intranet APIPA is enough.



Exipheas said...

The correct Network ID is and the Broadcast ID is the assignable addresses for this class B network are to

Siju George said...

Thank you Exipheas,

You are absolutely right. The network id of APIPA is

While writing the network id on my post ,actually what was in my mind is the first valid IP address in APIPA. The first IP address is

I understand my second mistake (broadcast address). I don't know why did I made such an error while typing the post. I will edit that error soon. Once again my thanks to pin point the mistakes I made.

Anonymous said...

Do you know if there is a way to determine the IP's of all connected stations?

Let's say I have 5 computers in a LAN and they assign themselves an IP by APIPA.
Now I can only access one machine (because the others are embedded systems), how can I find out the other IP addresses?


Siju George said...

@ Alex

APIPA is assigned by the OS it self and there is no external DHCP server works for it. So I don't think there is any way to find the APIPA ip address of other computers in the LAN without checking each system manually.

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jade craft said...

guys can you help, my hp pavillion cannot change the Ip 169.254.x.x i have already ipconfig/release=ok renew=error im using win7 the laptop can communicate trough other computer in the network that has an ip of 192.168.x.x my other pc can access the net. but the laptop cannot access internet help plz im troubleshooting this for 3 days and i have no luck...

Admin said...

I recommend you to assign a static IP address in hp pavillion in 192.168.X.X range and check for the issue. To know more about this issue follow the link below.

How to Resolve APIPA

Anonymous said...

Hi,the post is really good and informative.I have one doubt suppose there are five machines connected to a switch and 3 of them are getting ip address from DHCP server and 2 of them are getting the APIPA.So my question is will the 2 APIPA machines communicate with the other 3 machines? and will the 2 APIPA machines communicate each other please reply.

Admin said...

1. Your APIPA machines cannot communicate with other 3 devices getting IP addresses from external DHCP server since they are in different network address.

2. APIPA machines connected in the same network can communicate each other