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Anyone else having problems with RCN and DNS? And any suggestions how to debug them?
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jducoeur
For the past week, I have been having extremely frequent name-resolution issues on my machine at home -- the browser sits there at "Resolving host..." for a non-trivial amount of time (multiple seconds) on a large fraction of pages, and comes back with "Google Chrome could not find [foo.com]" pretty often. The problem *tends* to fix itself if I retry, but not always, and it seems to be getting worse -- today I'm finding it entirely impossible to get through to some sites that were working fine last week.

I'm not at all sure where the problem is. Before I go hassling RCN customer support (which I'm sure will be a delightful process), anybody have any suggestions on how one puzzles this out? This sort of low-level network operations problem is well outside my expertise.

(Using Chrome on Windows, on a theoretically secured and reasonably high-speed wireless router connection, if any of that is relevant...)

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I had a similar problem.

I run my own local DNS server, allowing me to add some local hosts for all the computers in the house. This works great, but I started having lookup failures. After a few days, I figured out that I had left the DNS server open to the outside, and someone was using it in a denial-of-service attack. (You can send a small DNS request that will cause the server to send a large packet to the target, so it is a bandwidth amplifier.) I blocked off the outside port, and now all is good.

If you're not running your own server, it's possible that someone is doing this to RCN's server, but I would expect they would catch that quickly and fix it.

You can always use Google's DNS at 8.8.8.8 and 8.8.4.4. It's fast, reliable, and doesn't muck with the results. It does give Google statistical data based on your usage, though.

I run my own local DNS server; if all you want is local resolution and caching, it's a very small and easy install.

If you don't want to use Google's DNS servers, you can also use OpenDNS's servers 208.67.222.222 and 208.67.220.220,
giving a different organization your statistics.

Not running my own DNS server -- I've got a pretty vanilla Windows setup, really -- so that's not the problem. But I hadn't thought about using Google's DNS servers. Very intriguing idea, and would help me prove that the problem is the DNS service from RCN. Thanks!

Depending on your version of windows, it should be fairly easy to set up automatic fail-over to a public DNS (or set it up as a secondary DNS source). Which is what I generally do.

I still get connection issues when my modem loses connection (which happens more-than-daily; thanks comcast), but it minimizes the name service issues.

My usual advice is to pick two (from different providers) from one of the many lists of public DNS servers. (Personally, I use 8.8.8.8 and 4.2.2.4, mostly because I long since memorized them.) Most consumer ISPs sooner or later get the clever idea of using DNS as a revenue stream, generally by some variant of pointing typos at advertising sites. I tend to figure not using your ISP's DNS gives them one fewer ways to piss you off.

I have had that same problem using the browser on my phone, usually only when it is on one particular neighborhood open wireless network. I haven't yet identified which neighbor has that open wireless network, so I don't know exactly where that issue is coming from.

Is your router acting as a DNS proxy? Most of those implementations suck. Try setting your machine to use the Google servers directly.

I run a local DNS cache which helps, but it should be fairly trivial to point your router at an alternate source of DNS, like OpenDNS or Google (8.8.8.8, although they had some issues of their own yesterday).

(Deleted comment)
It's *probably* not my modem, since that is recent. (Replaced middle of last year, when I got my new router.) But yeah, if it persists I may just have to pick a different DNS server...

Are you using a different DNS? I'm having really slow DNS response today at home--and checking, I'm using Google's DNS servers right now...

Weird. Network includes other comments for this post not loading until after I commented.

Anyway. Good info here.

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