BT DNS Issue

Rattlehead_ie

Hey guys, this is strange one and I cant seem to figure it out. At this stage its up to me ringing BT but I want to have ever possilbe avenue troubleshooted from my side.
Every so often maybe least once a day I loose connection to BT's DNS Servers only. The DSL light on the Zyxel 630 stays on but just all of a sudden instead of being able to browse my name i can only browse by IP. I have replaced the Modem with a Netopia from Eircom, Ive also taken out my local Linksys router just incase. To fix the issue usually I just turn on the Zyxel wait a min and turn it back on, but not always the case sometimes this goes on for hours.
There are NO phones in the house and only the one socket, i have tried this both with and without the splitter.There are 3 clients on LAN side and its not virus or spyware as all 3 are effected at the same time. I could use another DNS server but I'm wanting to know has anyone else come across this or have any idea's as the cause of this. Im living in Ranelagh and as far as my geography is, Im sure im pretty near the exchange.

kco3d

Just signed up to BT about 2 months ago and noticed the same thing. I set my DNS server (think to the same eircom use) manually on my router so not a problem now.....

TheHairyFairy

I'm with BT in Northern Ireland and have the exact same problem, started happening about a week ago. I havent been able to test by browsing by an IP address so will test that next.

vibe666

hands up who's using bittorrent or another p2p type application?

i've had the same problem for ages and so have a lot of other people.

the problem usually manifests itself as ip address based services working fine, but web pages just give 404 errors.

you should find that rebooting your modem will fix the problem, if it does, this is a sure sign that this is the problem.

you can try manually entering specific dns servers into your router and/or connection settings in your OS which sometimes helps if you're not torrenting.

long story short, basically what is happening is that you modem/router tracks tcp connections for anything up to a week (dep. on the model) after you actually use them, so when you add that to using a p2p app that uses anything up to thousands of ip addresses during the course of a day or so you get dns timeouts cos there's no room left in the modem for these entries.

now i'm not an expert, i've just had a lot of time to deal with the problem and this is what i've been told, so don't take it as gospel, but from what i understand this is the case.

if this sounds like your problem, you can forget BT or whoever heping you out as they really don't care.

the way i got around it was by getting myself a router that allows you to manually adjust the tcp tracking connection settings.

my choice was a linksys wrt54gs and the thibor 3rd party firmware. not all wrt54g's can take a 3rd party firmware tho, so have a good look on www.linksysinfo.org for all the info you'll need on the hardware and 3rd party firmwares.

some other makes of modem/router also do the same thing, but i hven't used them myself. thibor works a treat tho, and i highly recommend it as it has many benefits apart from that.

you'll keep your old modem and use it in bridged mode so t's basically just a dumb modem with the wrt54g doing all the work of connecting and managing your clients.

hope this is of help to someone as I spent an age trying to sort my connection out myself.

Thomas_S_Hunterson

Yup i've had the same problem. Rebootin the modem did the trick

jor el

I've had similar DNS issues in the past so now I just set the DNS server address when I set an IP address on any machine connectiong into the network. The BT DNS servers are 194.125.2.240 and 194.125.2.241. I think you can set these in the router config too, but setting it on the TCP/IP properties always worked for me.

vibe666

i know they're the ones BT auto assign when you connect, but Ive had more luck with these, which were recomended by a boardsie ages ago:

192.111.39.1
192.111.39.4

CuLT

Seeing as we're posting good DNS addresses, the ones I use are:

4.2.2.1
4.2.2.2
4.2.2.3

Gone West

CuLT wrote:

Seeing as we're posting good DNS addresses, the ones I use are:

4.2.2.1
4.2.2.2
4.2.2.3

thats in the Level3 IP block, yes?
I don't know, I used to use them, but you might as well just use the BT ones if youre on BT broadband. At least theyre based in Ireland, etc

vibe666

i'd be tempted to say that servers from a veriety of sources would be your best bet. not all your eggs in one basket so to speak, but i'd say the the chances of all the bt dns servers going down without taking your connection with them is slim anyway.

but can't hurt. not all dns servers are 100% correct all the time. where ones might fail the odd time ts better to have a good alternative.

Rattlehead_ie

Nice one Vibe, thanks Im looking into that.Ive a WRV54G so I dont think there is as much 3rd party software availabble for it but looking into it now.
I do use bittorren but i did stop this for a long time and it still caused issues, so I didnt think it would be a router issue. Out of curiousty how did u find out about this?just alot of troubleshooting??

exiztone

Yes, this happens to me too. It can be got around easily but just setting your DNS servers in your operating system rather than the router itself. I haven't had a problem since I've done that

daveirl

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