DNS issues windows 7 ultimate x64

Start - Accessories - Right click on command prompt and select run as admin.
Fire the command,
ipconfig /flushdns

Have you enabled DHCP or given a static IP address. If static, /renew or /release doesnt work.

Hi v432,

This could be caused by a number of things, locally (on your PC), Network (interference, dropped packets etc), Your router or modem (nad any cable connections in between if you have both devices), another device on your network (especially if it is issuing DNS), Connection to ISP (dropping packets), ISP's DNS server (issue here beyond your control). As you troubleshoot this, look for errors at each point along the way.

Locally (on your PC)

• Event Log Info: Is there a corresponding error number in the windows event log? (type eventvwr.msc in RUN or search and look through the logs). This will help us pinpoint the issue.
• Check the DNS Service: Does the DNS service fail (type services.msc in RUN or search for DNS client and check it), this test ascertains if the problem is your DNS service.
• Check for other broadcasting DNS': While in services, please check that you only have the DNS client installed (nothing else that says DNS and that it is set to start automatically). This ensures that DNS is not being issued from your PC.
• DNS are you there?: When your browser crashes. Open an elevated command prompt and type IPCONFIG /ALL. In the results, verify that your DNS address is correct, also please check if any other details such as 'default gateway' are missing. If DNS is correct, type PING x.x.x.x where x.x.x.x is the DNS address, does it answer? do this for any secondary DNS servers that you have. If only one answers that swap them around in your modem/router configuration.
• Check for Proxy's: Open your browser, for Internet Explorer, right click on'tools' and go to 'Internet Options'. On the 'Connections' tab, click on 'LAN settings'. Ensure that the 'Automatically detect settings' tickbox is ticked, that no configuration script is in use and that you are not using a proxy (unless you have purposely changed these before).

Out of curiosity, are you sharing out the internet connection on this machine? (on the wireless connection properties on the sharing tab, check if "allow other network users to connect through this computer's internet connection" is ticked). If so just untick this, as we move forward.

Other Network & Router stuff

• Interference: Try changing your wireless connection to another channel in case there is interference.
• Alternate DNS: THis is already mentioned I think; but check your ISP's website or call them, sometimes they have alternate DNS servers that may work better for your area.
• Reconfigure: I know it's pain, so save this for later, but you may just need to reset the router and reconfigure it. My Linksys wireless N has had me doing this twice in the last 3 years (which sort of serves me right for getting one of the first pre-standard wireless N models :) )
• Flash your firmware: Just like the above, you may consider flashing your router/modem with the latest firmware or at least investigating if your issue is common on your device.
• Connectivity test to find point of failure 1: On your PC open an elevated command prompt and type PING x.x.x.x -t, where x.x.x.x is the address of your router. Leave this running for 10 minutes and watch for dropped packets. This tells us the problem is router connectivity. You can stop this process by pressing CTRL+C.
• Connectivity test to find point of failure 2: Repeat the above process for your DNS servers, leave it for a while. (if you want to leave it for a long while, then change the command to PING x.x.x.x. -t >>%userprofile%/desktop/afile.txt. Where x.x.x.x. is your target address and %userprofile%/desktop/afile.txt is the txt the location and name of a text file (my exampel drops it on your desktop; you can change these around to suit; but there are a few locations where the permissions may not let you drop).
• Routing with port forwarding:If you've set up any port forwarding on the standard browsing or protocol security ports, we would also need to look at influences at the both ends of this. This is very doubtful for a home user and shouldn't be a problem unless they are forwarded to another PC on your network; but we are a forum for everyone I've posted it so check for forwarding on these ports L2TP (1701), PPTP (1723), SSTP (443), HTTP (80), HTTPS (8080).
• Other DevicesAs the problem is intermittent, it could occur when other devices enter your network and their ipaddresses are refreshed. Therfore, have a look at network printers, game devices (PSP, XBOX, Wii etc), IPOD's/PAD's, mobile phones and other network enabled devices that connect to your wireless and cabled network. Now ensure that these are not sharing an IPADDRESS with anything else. On the same note, you may wish to look at the attached devices page in your router configuration and check if all attached devices are shown. Missing devices that are turned on, could point to the same issue.
• MAC Changing: Lastly, if you ever used MAC changing software, remember to set your MAC addresses back to normal as this can confuse DNS servers that rely on MAC addresses to allocate your IPaddress

NOTE: The ipconfig /flushdns solution mentioned by zigzag3143 above is useful when you have a dynamic address (as dre@ms mentioned). This is used to flush, old or damaged DNS records.

Well this turned out to be a novel *grin* and a lot of it may be irrelevant. I included it all because you mentioned that you have already been searching for some time for a solution.

If you need clarification on any of the....erm.... chapters above, then just let me know.

Tim

Since your router/access point is an early n device and you are now using n that is most likely your issue. Try using g and see if all the problems go away. If they do then you know that the n wireless is the problem.