DNS issues need advice from network gurus

Got a weird issue with the interwebs.

My ISP has a couple DNS servers they offer and the router is set up with those in the primary and secondary. Every several hours, or every night around 8 or 9 (I can't figure out a pattern yet), the internet basically stops working, as in, new webpages will not load but existing pages and streams continue to work. If I swap the primary and secondary DNS servers, it starts working again instantly.

So, I figure the servers are jacked up and switch to 8.8.4.4 (google public dns). Same issue.. after a few hours it stops working and I have to switch it to something else then it starts working again. This leads me to believe its not the DNS server but my hardware or some configuration that is failing.

I have no idea what this means, it doesn't make ANY sense to me at all. Is there a DNS cache that could be filling up? A possible router issue? Some kind of hardware conflict timing out DNS requests? How can I troubleshoot this issue?

Try to access a site by IP during that period. I had a home internet connection once that would drop out at certain hours. They said a higher priority customer was doing a backup or something.

What will that tell me?

Originally Posted by kuksul08

What will that tell me?

If you can reach a website by IP (during that time) that will mean that your DNS is messed up.

If you can't reach a website by IP (during that time) that will mean that something else is broken (possibly DNS also is an issue).

i will try it and report back.

Is this a home network the with a modem from the ISP that you plug directly into?

If above is the case do the following. Log into the ISP's modem and make sure that the correct DNS servers are configured.

Don't rely on DHCP and statically configure your PC's IP and DNS settings. If your Internet takes a dump on you again see if you can ping by IP, if not most likely it is a PC issues. Does the problem happen after your PC goes to sleep or hibernation?

Also get a firewall or some sort, plugging directly into a modem is an absolute joke. When I say firewall I mean more then just your soho D-LINK router but a Cisco ASA for example.

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No the ISP uses a router basically to distribute the internets so I'm not sure if there is a modem.

OH I should also mention that if I turn on another computer in the house, it starts going slow, but if I change that DNS server in the router it will start going fast again. So I'm thinking it has to do with the router or my computer settings.

Get some SS of your NIC's(both PC's) and router config. I'll tell you what's wrong in about 5 seconds after looking.


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What part exactly of the NIC should I screenshot?

Alright it messed up again around 8PM so I took a screen of the settings. Just covered up IP and MACs. I'm not sure how subnet masks work, thats the only thing that stands out to me.

So I changed the DNS server to xx.xx.xx.x4 from ...x5 and it instantly started working again.

I also tried E46Fanatics via IP directly and it didn't work.

Why is your WAN IP address a static IP?
You paying for a static IP? If not, change it to DHCP.

If your ISP kills the lease on your IP, that would explain your issues

Wouldn't hurt to flash the firmware on that router too

That's how the ISP does it for all the customers in this area, they assign static IPs to each customer. It's not an option or extra cost. I don't know if they have a DHCP set up so it may or may not work if I switch it.

Can you explain how ending a lease on an IP would be corrected by changing the DNS?

Originally Posted by kuksul08

That's how the ISP does it for all the customers in this area, they assign static IPs to each customer. It's not an option or extra cost. I don't know if they have a DHCP set up so it may or may not work if I switch it.

Can you explain how ending a lease on an IP would be corrected by changing the DNS?

The Internet wouldn't work without DNS
It runs everything

Different DNS servers have different A and PTR records in cache.
They perform iterative and recursive lookups against domains, other servers and IP pools.

Stale DNS record... No more internets

You're running an 802.11B router from like 199 ****ing 5. Throw that garbage piece of **** out, that's why your internet won't work.

Originally Posted by JonJon

The Internet wouldn't work without DNS
It runs everything

Different DNS servers have different A and PTR records in cache.
They perform iterative and recursive lookups against domains, other servers and IP pools.

Stale DNS record... No more internets

So you're saying the DNS is failing?

Shouldn't something like google public dns 8.8.4.4 always work?

Yeah this router is old as hell, but that shouldn't matter right?

Flash it. Firmware is a decade old

The most recent firmware is 9 years old

I'll flash it anyway.