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There are perhaps a gazillion ways to speed up your network access when using Windows. I happened to come across one that fixes a nagging attribute that can sometimes trip you up. Be warned, however, that you’ll have to make a registry edit. This pertains to Microsoft XP and Vista. I don’t know Windows 7 well enough to comment on it yet, so you may want to check this with Microsoft before making this change.

Here’s the problem: You want to go to a website, so you enter the URL address into your browser, and you fully expect the website to appear. But for some reason, you get a mysterious message about the website being unavailable. For example, I use Verizon FIOS, and I’ll get a Verizon web page that says, “Sorry, ‘www.xxxxxxx.com’ does not exist or is not available.’ This could be the result a temporary network problem due to congestion. The network problem may be resolved in a few seconds; however, it’ll take your PC at least 5 minutes to recover from this situation. In other words, even though the network is working, it takes your PC five minutes to figure it out.

So what’s going on?

Deep inside your PC, there is something called a “DNS cache.” The DNS cache holds information regarding websites and their corresponding IPv4 addresses. For example, when you type “www.cnn.com” into your browser, it equates that symbolic address with the real IPv4 address of 157.166.255.19. This IPv4 address is needed by your router in order to route your website request to CNN. With millions of symbolic addresses out there, most PCs do not keep a copy of the symbolic addresses and their corresponding IPv4 addresses; rather, they submit the symbolic address (e.g.; “www.cnn.com”) to a designated DNS server, and the DNS server provides the PC with the IPv4 address. Thus, it’s a two-step process to connect to a website: Step 1 is to resolve the symbolic address to the website, and step 2 is to send traffic to the IPv4 address of the website.

 

 

This two-step process is expensive in terms of time and network traffic. To help reduce time and network traffic, most computers – including your PC – will hold a small list of your recent symbolic addresses along with their corresponding IPv4 addresses. So the first time you go to the CNN website, your PC will go to the DNS server to get the IPv4 address, but thereafter, it can just use information it already obtained during the previous DNS query, which is sitting in the DNS cache.

DNS query results are typically held in the DNS cache for 24 hours. This is not normally a problem, unless the target website changes its IPv4 address. The chances of this happening are fairly remote, so there is no harm in holding the information for 24 hours. However, there is a problem when the original DNS query fails. While information from successful queries is held in the DNS cache for 24 hours, information from unsuccessful queries is held for 5 minutes. Therefore, if there is some temporary network problem that prevents your DNS query from being successful, your PC will “remember” this failure for 5 minutes. If, during that five minute period, you try again to contact the website, your internal DNS cache will remember the failure and you will get the same results.

So how can you fix this problem? You simply have to tell your PC to not allow failed DNS attempts to get into the DNS cache. To do this on a XP or Vista machine, you’ll need to make a registry change.

You can change the registry value by running “regedit.”

1. On an XP machine, this can be accomplished by hitting the Start button and entering “regedit” in the command box. On Vista, you hit the Start button and type “regedit” in the search box.

2. Locate the registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\ CurrentControlSet\Services\Dnscache\Parameters

3. Create a New entry: DWORD (32-bit).

4. Name the entry NegativeCacheTime

5. Set the entry value to 0. It should default to that value anyway.

6. Close the regedit window.

From this point forward, your PC will not remember unsuccessful DNS attempts in the DNS cache. So your PC should be able to recover as fast as the network.

Best,

Dan

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