NAT stands for Network address translation.  This methodology is used for modifying the network address information in the IP datagram packet headers while they are being transmitted across a traffic routing device.  The porpose of this is for remapping one IP address into another IP address.

Why would this happen?  Well this happens quite often.  One reason for this could be that a company has outgrown its hosting company and had to move it’s entire site from one set of servers to another.

You can’t just switch the name servers of a domain name and expect the entire site’s contents to be instantly moved.  This process can take quite a lot of time and if you are inexperienced in doing this, please consult an expert before you try and do this yourself.  It will end in disaster and you will lose all of your hard work in an instant.

Make sure you do a backup before moving the website’s files from one server to another. That way if things do end in disaster you will be able to restore your website.

When you move a website and all of its contents, it takes the internet quite a while to catch up.  The previous hosting company will have to redirect traffic to the new website address.  This is what NAT does.  It readdress the incoming and outgoing packets to ensure that they end up where they are supposed to go.

All of this can take up to a couple of days just to get the website moved, but can take weeks for the internet to catch up with the new addresses.  So until the internet catches up the NAT will make sure that the information gets where it is supposed to go and that outside visitors can get to your site.