uTorrent causes router loss of DNS connectivety

Occasionally (every 4 or so hours) my router loses DNS connectivety
(or the ability to forward my dns inquires). This only seems to happen
when I am downloading torrents, so I assume it is related. I use
"uTorrent" as my client. I've experienced this same phenomenon on
three different types of routers now over the past year or so. It's
something I've battled with quite a few times.

If anyone else has experience with this specific problem (routers
+torrents=dead dns) I'd love to hear your thoughts! Am I just
overwhelming these puny cheapo $30 routers? I read something about the
router NAT tables getting overwhelmed then disrupting DNS, anyone have
more info about this? Will a better router solve my problems?

More Details:
- I'm not a complete moron (meaning: the router is plugged in & turned
on, etc etc!)
- On the router(s) I set port forwarding correctly for the torrent
software.
- This loss of DNS connectivety affects all LAN computers at the same
time, regardless of if they are wired or wireless.
- It happens every 1-10 hours randomly, usually when the router is
under a fair amount of stress (overheating???).
- All computers retain LAN and WAN conectivety; meaning I can still
connect to my shared folders & my torrents are still moving.
- Running NSLOOKUP from dos confirms there is no DNS connectivety.
- I cannot connect to the router via the browser when this is
hapenning
- I've experienced this on 3 different routers: a DLink WBR-1310
Wireless, a Gigafast WF719-CAPR Wireless, and some unknown 4 port
Dlink wired.
- Note: all three routers were "cheapo" models.
- Main computer is running Xp Home and the torrent software.
- I have tried both dynamic and static IPs and DNS settings on the Xp
Home machine.
- I have tried both Zonealarm and Sygate Firewalls. I dont use WinXP's
Firewall. I've tried disabling all firewalls completely.
- I have tried lowering the maximum amount of connections uTorrent can
make, down to 20.

Below are two similar (unsolved) posts I found on google:
http://tinyurl.com/2fqkpg
http://tinyurl.com/262m35


Any thoughts would be appreciated. I'd like to know exactly what's
happening here.

Re: uTorrent causes router loss of DNS connectivety

dennispublic@hotmail.com wrote:
> Occasionally (every 4 or so hours) my router loses DNS connectivety
> (or the ability to forward my dns inquires). This only seems to happen
> when I am downloading torrents, so I assume it is related. I use
> "uTorrent" as my client. I've experienced this same phenomenon on
> three different types of routers now over the past year or so. It's
> something I've battled with quite a few times.

{snip}

> Any thoughts would be appreciated. I'd like to know exactly what's
> happening here.
>

The only thing I've seen work somewhat reliably is reducing the number
of concurrent connections you allow. This is different than the number
of active torrents. The reason (as I've seen it) is that if you let an
unlimited number of connections occur, you actually DO overwhelm your
router and it begins to hiccup.

A small word of warning about downloading torrents though... Most
torrent sites (possibly all) record your IP when you connect to a
torrent and that data gets added to "trackers." The next client that
accesses that torrent will receive a list of IP addresses known to have
all or part of the file, and will attempt to connect to you to get a piece.

If you access a popular torrent file, this can quickly snowball into a
LOT of requests being sent your way. This can interfere slightly with
your available bandwidth.

If your router supports logging, take a look at all the incoming
connection requests on the port you use for torrent transfers.

Re: uTorrent causes router loss of DNS connectivety

Just to ensure it's not your ISP sucking or your router overheating or
something like that why not try a different torrent client?

Also how long does this inability to do DNS lookups last? Or what do
you do to resolve the issue?

Re: uTorrent causes router loss of DNS connectivety

On 8 Feb 2007 23:35:15 -0800, dennispublic@hotmail.com wrote:

>Occasionally (every 4 or so hours) my router loses DNS connectivety
>(or the ability to forward my dns inquires). This only seems to happen
>when I am downloading torrents, so I assume it is related. I use
>"uTorrent" as my client.

I experience the same thing very infrequently and I use Azureus.


Tom

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Re: uTorrent causes router loss of DNS connectivety

dennispublic@hotmail.com wrote on 8 Feb 2007 23:35:15 -0800:

> Occasionally (every 4 or so hours) my router loses DNS connectivety
> (or the ability to forward my dns inquires). This only seems to happen
> when I am downloading torrents, so I assume it is related. I use
> "uTorrent" as my client. I've experienced this same phenomenon on
> three different types of routers now over the past year or so. It's
> something I've battled with quite a few times.
>
> If anyone else has experience with this specific problem (routers
> +torrents=dead dns) I'd love to hear your thoughts! Am I just
> overwhelming these puny cheapo $30 routers? I read something about the
> router NAT tables getting overwhelmed then disrupting DNS, anyone have
> more info about this? Will a better router solve my problems?

Whenever I've experienced this, the solution has been to change the PC DNS
servers to those of my ISP. In the routers I've used in the past (all of
them Netgear), if you have the option enabled to automatically get the DNS
servers then the DHCP settings cause the PCs on the LAN to use a DNS Proxy
on the router itself, which very quickly gets overwhelmed when using a
torrent client. By setting the PC to use the ISP DNS directly (or in the
case of a Netgear router by turning off the "Get DNS from ISP automatically"
option and instead entering the DNS server addresses themselves, which them
results in those addresses being passed out via DHCP) I no longer saw DNS
resolution problems with my routers.

While I have no experience of the routers you are using, I'd suggest giving
it a shot. These cheap devices have very little RAM and little processing
power, and trying to maintain a large DNS cache just seems beyond them when
the rest of the system is trying to use those resources too.

Dan