Always finding the best DNS server to use

[csdude55]

I don't have the fastest home internet service, maxing out at 6M on it's best day... but more commonly around 4M. But I've found that I can use a public DNS, and that often makes things faster.

I USUALLY set Google DNS (8.8.8.8, 8.8.4.4) at my router, but sometimes it will slow down to <1M. Then I change it to OpenDNS, which is sometimes faster... sometimes not. If not then I flip over to Cloudflare. And last in the list, I let my internet provider set one. I run Google's speedtest after each change, and then just stick with whichever is fastest.

The question is, can you guys think of any way to automate this, so that I'm always running the fastest DNS? Some days (like today) it's just a constant routine of testing, changing, wait an hour, test again, repeat.

[Kendo]

Is this about your Internet connection at home?

If so, why not use the DNS provided by your ISP.

[phranque]

i'm not sure how the dns used would have a significant effect on google's speedtest.
once you make your dns request and have the IP address, it's not like you're uploading/downloading bits through the dns.

[csdude55]

I have CenturyLink at home. I can't tell you how many times I have the same experience... I'm watching Netflix or something, and the video goes blotchy or stops connecting altogether. I stop it, do a speed test... 0.15M or something.

I restart the router, no change.

I change the DNS to one of the others, do a speed test, and it's suddenly at 6M.

I've tested a million different ways, and the only thing that seems to change the speed is changing the DNS. I've tried simply flushing the DNS, rebooting the router, rebooting the Roku, nothing else has any impact like changing the DNS does.

[Kendo]

once you make your dns request and have the IP address

DNS lookups happen once and are then cached. Sounds more like your ISP is throttling your bandwidth, or the destination server is.

[csdude55]

Hmm. I see. So you're saying that it's a coincidence that changing the DNS server "fixes" it?

[coopster]

One thing to note, if your router has an IPS function (Intrusion Prevention System), it may be your issue. I upgraded my CenturyLink connection to 60Mbps a couple years ago and noticed during speed tests that I was running at only 25% of this and after a direct test from the WAN side of the router, full 100%. Disabling IPS and testing again from behind the router, 100%. I happened across this information via a Cisco forum discussion [community.cisco.com].

[NickMNS]

You could try Cloudflare's DNS resolver service:
[cloudflare.com...]

[Kendo]

So you're saying that it's a coincidence that changing the DNS server "fixes" it?

Probably because in doing so that you also creating a new connection and a new session (for the download of movies is it?).

[csdude55]

for the download of movies is it?

Nah, I lost interest in that before Limewire was shut down :-) It mostly happens while watching Netflix or Hulu, but lately it's been REAL bad.

Maybe I'm being throttled over emails. I couldn't find a good way to export from Thunderbird and import to Outlook, so I've been uploading to my IMAP'ed Gmail in Tbird and then downloading them back to Outlook. I didn't think I was doing THAT much, but that's the only thing that's changed.

[iamlost]

Two things:
1. Don’t just run a speed test. Run traceroute both when things are running ‘normal’ and when they bog down. The normal over time provides a benchmark and the ‘bogged’ will indicate bottleneck, which info is more helpful when talking to customer service than ‘things are slow’.

2. CenturyLink is known for peering ‘difficulties’. Especially when connection goes through certain Level3 (acquired 2016) nodes.
For instance, it is not uncommon to see each hop timing at 5-15ms then encounter Level3 nodes timing at 200-300ms.

Best wishes.

[Kendo]

It mostly happens while watching Netflix

But isn't that about downloading movies? There is no difference between "watching" and "downloading" because in both cases the video has to get to your computer.

[phranque]

There is no difference between "watching" and "downloading" because in both cases the video has to get to your computer.

without further details, i would assume a "download" implies an http request and all data is transferred through that protocol.
i'm not a netflix expert but i would assume a streaming service on roku (for example) transfers data through sockets using some other protocol.

[Jonesy]

Another good utility to check problems such as this is the *nix program `mtr`