Then it spends a few seconds timing out to that server.įinally, I was able to reduce the initial waiting period from 15 seconds to 2 seconds by putting the server into lmhosts. It doesn't get an answer, and then somehow gets the right IP (10.0.2.15), perhaps via DNS. It looks like it does a UDP broadcast to the whole subnet (172.27.8.255). You can see the 15 seconds the initial request is taking. Instead, I got a capture from Wireshark showing Netbios naming service packets: But I couldn't find any knobs to turn in Windows. Address Resolution Protocol (ARP) requests can be used by Wireshark to get the IP address of an unknown host on your network.
I was trying to find a way to configure both the maximum amount of time a request to a non-existent server can take (the 15 seconds), as well as how long the fact that the server is down is cached (the 10 seconds). So there is actually a caching mechanism for unavailable servers. Then there is another 15 second timeout, and the pattern repeats. Subsequent requests fail quickly for the next 10 seconds or so. If you capture the NetBios traffic with a tool such as WireShark you should see something like this: (192.168.1.18 is the PC. If for some reason DNS doesn’t know where that host is, your computer will send out a NBNS and/or LLMNR request. NBNS works fine, remember that NetBios names can't be longer than 15 characters your example has 18. I ran some tests using ColdFusion, and I noticed that if you request a file on a known-down or non-existent server, the initial request takes 15 seconds to timeout. It contains all the systems and their addresses on the network. That whole time, the browser request is hanging out waiting for the web-server to respond. But the web-server waits for a handful of seconds before it's sure. It lets you capture and interactively browse the traffic running on a computer network. If fileserver1 is actually down, then no response is coming. Wireshark® is a network protocol analyzer. Pop open Wireshark on your home computer, set the capture filter to udp port.
WHAT IS WIRESHARK NBNS WINDOWS
What's happening? The Windows web-servers are actually making NetBIOS broadcasts, asking your network "hey, is anyone fileserver1?". If your product is a website, and the web-servers make a lot of file requests, one of the fallouts is that requests will start to pile up. If you have a production file server failing, you have serious problems.
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