Sometimes the only way to find out what is going on or why something is not working is to capture and analyze network traffic using a packet sniffer, also known as a network analyzer.
Microsoft has written a full featured packet sniffer named Network Monitor 3.4 (http://blogs.technet.com/b/netmon/p/downloads.aspx), which is available as a free download.
To get you started with this essential network troubleshooting tool, the Network Monitor team has published a series of videos here (http://blogs.technet.com/b/netmon/p/usagevideos.aspx), which provide an overview and show you the basics of capturing, filtering, and automating Network Monitor functions with PowerShell.
To keep up with the latest news about Network Monitor, see the Network Monitor blog (http://blogs.technet.com/b/netmon/).
Joe DaviesPrincipal WriterWindows Server Information Experience