An exception you might know that there are through different port numbers that are available for TCP in UTPA now as applications are running on abuse networking you may have a computer that has fifty different network applications open at a time using up fifty different port numbers now you might think as you start pondering things that could happen what if two devices happened to generate the same source port number at the same time what then.

I mean what how to handle that it when both those requests came to the router and they were both using was a source port the routers prepared for that because that’s actually a very common circumstance because with a busy now working lots applications you can get into thousands a port numbers in use at a time so the chances multle computers will use the same one the router has no problem handling that whichever one gets there first and there will be a first you know because the router can only receive one packet at a time so one will be one millisecond behind the other which everyone gets there first will get the and go out as that now once the other one will say I - doubt forty-nine comes in with the source said as that comes in the router looks egos sorry man is in use I'll just give you the next Freeport so on map that one that forty-nine Colin to who at that one will say- to seems too.

simple right that but that’s all it does it just takes the next available port number and now when the communication comes back to it looks and says oh well I'll translate that port her AC why we call it pat are port address translation I'll translate that port back to the original that was sent from the client 642-902 finally the last warm-up match is known as static NAT this form is typically used for hosting servers inside your network for example we have private addresses here at: and so on those private addresses since they are private are not accessible from the internet that's the whole definition of privates that it is underground herbal by Internet routers so we have to use static NAT to map public address is here to private one so when somebody wants taxes maybe we have an internal web server maybe that's this guy running at our cum our company weekend for that request into the internal web server and allow people to access it that's known as a static.