how do i know if udp port 5353 is open windows 7?

If Windows Firewall is blocking a program and you want to allow that program to communicate through the firewall, you can usually do that by selecting the program on the Exceptions tab in Windows Firewall. To learn how to do this, see Allow a program to communicate through Windows Firewall.

However, if the program isn't listed on the Exceptions tab, you might need to open (add) a port. For example, to play a multiplayer game with friends online, you might need to open a port for the game so that the firewall allows the game information to reach your computer. Unlike an exception, which is only open during the time that it is needed, a port stays open all the time, so be sure to close ports that you don't need anymore.

1.Open Windows Firewall by clicking the Start button , clicking Control Panel, clicking Security, and then clicking Windows Firewall.

2.Click Allow a program through Windows Firewall. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.

3.Click Add port.

4.In the Name box, type a name that will help you remember what the port is used for.

5.In the Port number box, type the port number.

6.Click TCP or UDP, depending on the protocol.

7.To change scope for the port, click Change scope, and then click the option that you want to use. ("Scope" refers to the set of computers that can use this port opening.) Answered Feb, 27 2011

Did you mean opening a port in Windows firewall? If so, you should see this site. 

http://windows.microsoft.com/en-US/windows-vista/Open-a-port-in-Windows-Firewall

Answered Aug, 25 2010

you can read details: http://forum.kaspersky.com/index.php?showtopic=44732&st=0&p=408488&#entry408488

Answered Oct, 16 2010