[SOLVED] DNS problem when downloading big files on fresh Win10

[Nightsky1700]

Hello, I've recently upgraded my brother's PC, and I noticed a strange behavior with internet connection after installing fresh copy of Win10. When I was downloading nvidia geforce driver (~500MB) the interned went down. I just couldn't visit any page as I kept getting some dns error on the browser (different browsers). I tried ping yahoo - it didn't respond either. The weirdest thing among all, was that the download process was progressing just fine. As it finished, the interned came alive...I was shocked.

I tried to repeat the process, and it behave the same each time:
start downloading a big file,
after a while the interned is down,
the file is downloaded,
the internet is back...

I didn't touch the old HDD, with Win7 on it, so I plugged it back, and....it works just fine. I can download big files and browse the interned simultaneously - no problems at all. This kind of eliminates the router malfunctioning I guess...

So I searched a bit, and tried to set up google's DNS (8.8.8.8, 8.8.4.4) on my Win10 ethernet connection. It does fix the problem, however I still have this weird feeling that something is wrong underneath.

Why would a fresh copy of Win10 have problems with DNS being set to auto? Is there any explanation for that?
Why on my old HDD with Win7 (without any DNS modifications) everything just works?

Thanks in advance!

 

[Ralston18]

Fresh Windows 10 install - Windows may have been trying to do its' own updates and continually failing to do so at the same time as the downloads.

The download had, or took, priority.

The internet/network was not down per se. Just not able to keep up.

Temporarily disable Windows updates and determine if the problem continues.

Use Task Manager to see what all is running before a large download and then watch what changes during a large download.

Resource Manager can be used in much the same manner.

 

[SamirD]

Win 10 tries to be too smart just as each 'upgrade' has been since the days of win95. When the 'smart' is programmed wrong, this 'stupid' stuff results.

It also could be a momentary issue with that dns server if you system is hammering it with constant requests.

 

[Nightsky1700]

Some good input here I'll verify it this week, as I currently don't have access to thic PC. I hope it's temporary, and it will be working fine.

Thanks for the feedback

 

[beers]

It does fix the problem

What was your previous DNS endpoint, the router? If it's old or underpowered it may have hung on the daemon while maxing out the CPU for your transfer, therefore losing your query.

You should just be able to pop in those google DNS (or any other vendor) into your DHCP server so all clients inherit those values.

The weirdest thing among all, was that the download process was progressing just fine.

That makes sense though as the DNS name was already resolved for the transfer, so no further lookups required as the session was already established IP to IP.

 

[Nightsky1700]

What was your previous DNS endpoint, the router? If it's old or underpowered it may have hung on the daemon while maxing out the CPU for your transfer, therefore losing your query.

If you ask about ipconfig /all DNS section, there is the router's ip address.

That makes sense though as the DNS name was already resolved for the transfer, so no further lookups required as the session was already established IP to IP.

Hmm..sorry but I think I don't get your point here...the dns name was already resolved for the transfer, but at the same time when I wanted to visit any website, no more lookups were required? I'm not an expert in networking, but I thought each time I want to visit a page, then there is a lookup that resolves a domain name into the ip address... Maybe I got your message wrong, but for me it's strange to stop resolving addresses, until the download is complete.

I checked for both systems (Win7 and Win10) and everything is set the same on the connection properties, however on old Win7 it works fine, whereas on new Win10 it fails to resolve a domain name during download (until I change DNS addresses to e.g. google's).

Thanks for the reply!

 

[beers]

Hmm..sorry but I think I don't get your point here...the dns name was already resolved for the transfer, but at the same time when I wanted to visit any website, no more lookups were required?

New lookups for new sites, but the in-progress file transfer didn't require another lookup since it already completed a lookup (and the download continued).

If you ask about ipconfig /all DNS section, there is the router's ip address.

What router is it? Based on the behavior and resolution you're observing I'd blame either CPU resource contention on the router or the DNS subsystem/daemon on the router. You should be able to reference google DNS or similar directly from your clients and not have to rely on that DNS forwarder on the router. Then from the router's perspective it's just forwarding a DNS packet instead of proxying your request and doing its own lookup.

 

[Nightsky1700]

What router is it? Based on the behavior and resolution you're observing I'd blame either CPU resource contention on the router or the DNS subsystem/daemon on the router. You should be able to reference google DNS or similar directly from your clients and not have to rely on that DNS forwarder on the router. Then from the router's perspective it's just forwarding a DNS packet instead of proxying your request and doing its own lookup.

Ok, now I get what you mean. I got the router from my ISP. It's probably their product as there's my ISP's logo on it.

So assuming this is the router's fault - I'm still quite intrigued what's special about Win10 that causes router's cpu resource or dns system not being able to keep up...If I was able to reproduce it on Win7, it would be easier to blame it

Thanks!

 

[beers]

If I was able to reproduce it on Win7, it would be easier to blame it

Agree that is kind of odd, although it's also odd that the DNS change also fixes your flow. You might be able to pcap on that to see specifically what traffic is working or at what point it times out.

Otherwise it was merely a guess based on the behavior and resolution you were observing and may be coincidental, but at least you have a fix <3

 

[Nightsky1700]

Ok, so it turned out, that it was just a temporary thing. I turned the PC on, let it download all of the required updates, then installed them without any interruptions, and all is working fine now. Maybe the updates were interrupting a normal PC usage, maybe it was a temporary router's fault, but thankfully it all went well without re-formatting the drive.

Thank you all for your help!

 

[SamirD]

Strange stuff indeed, but glad that it worked itself out. Thank you for posting the solution!