SIOCADDRT: File exists Error

I was getting this error on a MFVE, but it is applicable to any Linux server with multiple NICs.

The Problem

I‘m typing the following command under Ubuntu Linux:

route add default gw 192.168.3.2 eth0

But it is giving me out the following error:

SIOCADDRT: File exists

How do I fix this problem?

The Solution

This error normally displayed when you try to modify or or add a new routing IP address. For example, when you set the same route multiple times you will get this error.
Understanding SIOCADDRT: File exists Message

1.SIOC: Serial Input Output Controller.

2.ADD: ADD (addition).

3.RT: RouTe (routing ip).

4.File exists – Routing is already configured so delete wrong one and add the new one.

Display Current Routing Table

Open a command-line terminal (select Applications > Accessories > Terminal), and then type the following command to see your current routing table:

netstat -r
or
ip route list