DNS issue with DHCP turned on - no internet
A neighbor's laptop was having problems connecting to the internet so I'm trying to diagnose and fix the problem.
Her Windows 7 laptop is normally configured for DHCP for ip and dns.
She recently allowed her laptop to receive a bunch of Windows updates but she's not sure that the updates correlate with when the problem started.
I've got the laptop at my house and it will only connect to the internet when I change DHCP to my ISP's DNS. I can leave DHCP on for IP address but DNS must be static otherwise it connects to my network (wired or wireless) but never can get to any web pages or her outlook email doesn't work. Plug in a static DNS and viola, it works. We are both on the same ISP (TWC Roadrunner Austin).
I might also mention, when I'm go back to wireless on this laptop, it takes about 1 minute before the signal bars at the bottom clear (no spinning circle). It still doesn't connect, but it's odd that it takes so long to try to establish a connection and I thought that might be helpful info.
My DHCP works well for the 10 other devices in my home that regularly connect to my wireless network so I've kind of eliminated my WNDR3700v4 router as a possible problem. I haven't done a system restore (yet), because I wanted to try to figure out the problem first if possible.
Would appreciate some troubleshooting tips before doing a system restore attempt.
Her Windows 7 laptop is normally configured for DHCP for ip and dns.
She recently allowed her laptop to receive a bunch of Windows updates but she's not sure that the updates correlate with when the problem started.
I've got the laptop at my house and it will only connect to the internet when I change DHCP to my ISP's DNS. I can leave DHCP on for IP address but DNS must be static otherwise it connects to my network (wired or wireless) but never can get to any web pages or her outlook email doesn't work. Plug in a static DNS and viola, it works. We are both on the same ISP (TWC Roadrunner Austin).
I might also mention, when I'm go back to wireless on this laptop, it takes about 1 minute before the signal bars at the bottom clear (no spinning circle). It still doesn't connect, but it's odd that it takes so long to try to establish a connection and I thought that might be helpful info.
My DHCP works well for the 10 other devices in my home that regularly connect to my wireless network so I've kind of eliminated my WNDR3700v4 router as a possible problem. I haven't done a system restore (yet), because I wanted to try to figure out the problem first if possible.
Would appreciate some troubleshooting tips before doing a system restore attempt.
Do you use DC in your network?
ASKER
Thanks John, I will look into that when I get home later today.
tankergoblin, sorry, what is DC?
tankergoblin, sorry, what is DC?
DC is Domain Controller and you probably do not have a Domain Controller here
ASKER
oh. duh. no, I don't use a domain controller on my home network.
then you can try to set secondary dns in your router or manually configure it in the problem pc. you can try to use 8.8.8.8 as your secondary dns.
ASKER
When I configure a static DNS IP in the problem pc, it consistently works and connects to the internet/mail, etc.
My router is already set up with googles DNS address as secondary and my ISP's DNS as primary.
My router is already set up with googles DNS address as secondary and my ISP's DNS as primary.
then you try ipconfig/flushdns as suggested by John see whether your problem solve ?
ASKER
John Hurst, I tried all of the steps you listed, but it made no difference at all.
I put google servers in the dns and immediatly worked. I also used public domain dns servers or my roadrunner dns servers, and it always works after that.
There must be something I'm overlooking. By the way I have a router with DHCP turned on and an access point with DHCP turned on. I've connected to both with DHCP, it makes no difference, won't work until I plug in a valid dns ip.
Same thing happens when I hardwire connect to my router, it wants a physical dns addy.
I put google servers in the dns and immediatly worked. I also used public domain dns servers or my roadrunner dns servers, and it always works after that.
There must be something I'm overlooking. By the way I have a router with DHCP turned on and an access point with DHCP turned on. I've connected to both with DHCP, it makes no difference, won't work until I plug in a valid dns ip.
Same thing happens when I hardwire connect to my router, it wants a physical dns addy.
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ASKER
John Hurst, SFC ran it's course but didn't find issues. I would consider using Windows 7 repair as my last resort but another thought occurred to me... I powered up my own laptop and turned on DHCP (normally I have a static IP for everything). My own laptop couldn't access internet sites until I added physical DNS addresses.
So my direction started turning to my router.
Coincidentally another poster (Predrag...) mentions this in the post after yours. I am going to investigate that at the moment.
So my direction started turning to my router.
Coincidentally another poster (Predrag...) mentions this in the post after yours. I am going to investigate that at the moment.
ASKER
Predrag,
I'm not at home now but will try what you are suggesting later. I have a sneaky suspicion this might work.
If it does then I'd ask why I have to plug in dns numbers into my router when all of that should be coming from my ISP (TWC in my case).
My router is setup the way your screen shot depicts, defaulting to get everything from ISP. This seems to work for 3 android tablets I use regularly at home to get to the internet, surf, check mail, etc. and those devices all use DHCP totally.
The only difference is my laptop is windows 8 and tablets are android.
I'm not at home now but will try what you are suggesting later. I have a sneaky suspicion this might work.
If it does then I'd ask why I have to plug in dns numbers into my router when all of that should be coming from my ISP (TWC in my case).
My router is setup the way your screen shot depicts, defaulting to get everything from ISP. This seems to work for 3 android tablets I use regularly at home to get to the internet, surf, check mail, etc. and those devices all use DHCP totally.
The only difference is my laptop is windows 8 and tablets are android.
In a last few months I had problem with providers here in my area, for some reason their DNS servers did not work (or client routers did not get DNS from ISP's servers), so I forced on many routers in a last few months to use google 8.8.8.8 and Level 3 Communications 4.4.2.2 as DNS.
And truth to tell many of those routers worked for years without bigger issue (except need to restart sometimes) and than at one point in time problems started, so far about 30 routers from home clients had the same issue pattern as your case.
And truth to tell many of those routers worked for years without bigger issue (except need to restart sometimes) and than at one point in time problems started, so far about 30 routers from home clients had the same issue pattern as your case.
ASKER
I may also try to hardcode my ISP's dns server numbers into the router as well but google's DNS addresses should be ok too. Thanks
ASKER
Predrag, it sounded like a good idea but it didn't work.
I used google dns servers and tried TWC's DNS servers, even tried OpenDNS servers, but it didn't change anything so I went back to the default 'get automatically from ISP" setting.
I also verified that my 3 android tablets can get out to the internet and they're all DHCP. So I guess this points back to my laptop.
I used google dns servers and tried TWC's DNS servers, even tried OpenDNS servers, but it didn't change anything so I went back to the default 'get automatically from ISP" setting.
I also verified that my 3 android tablets can get out to the internet and they're all DHCP. So I guess this points back to my laptop.
ASKER
It didn't fix my issue but it helped.
Thanks and I was happy to help you.
Open cmd.exe with Run as Administrator
Then netsh int ip reset c:\resetlog.txt
Also, ipconfig /flushdns followed by net stop dnscache followed by net start dnscache
Then restart the computer
You should also look in c:\windows\system32\driver