10.1 official: long delay during name resolution by web browser
 

PROBLEM: When I click (or type) a link in a browser, there is a long delay while the browser says it is resolving the hostname.

DETAILS: The delay is typically around 10 seconds, sometimes ranging up to 30 seconds.

SYSTEM: 1.1 GHz Celeron, 384Mb RAM, 160 Gb HD, Mandrake 10.1 Official single-booting from a clean install. System runs well in every way except this one (apart from Nautilus crashing, but that's normal). Connected via a 768kb/s ADSL link.

DATAPOINTS:
-- This is not a browser-specific problem, since Firefox, Mozilla, and Konqueror all behave the same way.

-- This is not a network transfer problem, since once the transfers start (after "Site found" messages) the transfers are generally fast, taking far less time than the name resolution.

-- This is not a problem with my network, because all the other machine connected to the same switch have no problem, including my ancient 133 MHz Toshiba running Vector 3.2, which resolves names far more quickly.

-- This is not a problem with the machine's hardware, because if I boot it up with a Knoppix CD the same browsers (Konqueror, Mozilla) resolve names in a heartbeat or two and then run just as quickly through the transfers. The same machine also ran Fedora Core 1 without any issues (but with a little less memory) until I installed Mandrake last week.

-- This is not an intrinsic problem with the DNS lookup of the installed system, since using nslookup, dig, or hosts all result in name resolutions in under a second (typically .79 seconds or so, and reasonably consistent)

-- I have tried turning off IPv6 by putting "alias net-pf-10 off" in /etc/modprobe.conf, as suggested in another thread (search for "slow DNS lookup"). It didn't seem to help, but then I note that Knoppix doesn't turn it off either.

QUESTIONS:
-- What's going on here? (Well, obviously :-)

-- This system is my first 2.6 kernel, is that part of the problem?

-- Is there a solution other than returning to Fedora Core 1??

Thanks in advance,
Mark

Try adding those 2 lines at the end of the /etc/modprobe.conf file:

alias ipv6 off
alias net-pf-10 off

Let me know if it works, I'll tell you why it did. I won't bother if this doesn't help you...

Amazingly, that seems to have done the trick. Thank you very much, and may the blessings of heaven be richly showered upon you.

I had the second line already in my /etc/modprobe.conf so the first is what made the difference.

Now, some more questions:

1. Why does turning off ipv6 make such a difference?

2. Why does Knoppix 3.6 with its 2.4 kernel not suffer the same problem, when the only non-commented line in its /etc/modules.conf is "alias net-pf-17 off"?

3. Why doesn't Mandrake set this up as default?

I look forward to further enlightenment on this topic.

Thanks again.

1. Why does turning off ipv6 make such a difference?

2. Why does Knoppix 3.6 with its 2.4 kernel not suffer the same problem, when the only non-commented line in its /etc/modules.conf is "alias net-pf-17 off"?

3. Why doesn't Mandrake set this up as default?

---------

1) Leaving IPV6 on results in your Linux box trying to first access IPV6 capable DNS servers on your network... which do not currently exist.

2) IPV6 was somewhat broken in 2.4 and requests were not actually transmitted quite often.

3) Because IPV6 is the "next" thing, so to speak, and turning it on is supposed to prepare things for the imminent future.

For the moment it's pointless to rationalize it, just take for granted that turning it off works...

I think opjose's answer is pretty clear. I'll just add that this seems to impact some 2.6.x Kernels as I've experienced this problem on several distros (Suse, Fedora, Mandrake).
This bug is documented on RedHat's web site, with poor info though, if you're interested here is the link:
https://bugzilla.redhat.com/bugzilla....cgi?id=124376

That worked for me too
 

Just wanting to add that this solution worked for me. I was having a problem where my web browsers were not able to connect to very many web-sites. It would connect to some sites and would ping some but not all. It was able to lookup the DNS entries for almost all websites, but was having problems transfering data between the site and my computer. I am running through an ADSL router as well.
Thanks for the info, you saved a big head-ache!
-Dan

AWESOME..... It worked for me too!!! TYTYTYTY

Only other problem I have now is I can't get any of my messenger services to connect. Not sure what's up there, but they will not work using GAIM or any other client.

still not working(slow internet connection)
 

this is what my /etc/modprob.conf contained

alias eth0 xircom_tulip_cb
alias sound-slot-0 maestro
install usb-interface /sbin/modprobe/uhci-hcd; /bin/true


I went into the terminal (did a su to go in as root) and typed this:
emacs /etc/modprob.conf
and added the lines so it now looks like this:

alias eth0 xircom_tulip_cb
alias sound-slot-0 maestro
install usb-interface /sbin/modprobe/uhci-hcd; /bin/true
alias ipv6 off
alias net-pf-10 off

and saved it.

However I'm still getting the huge lag. I'm on a t1 and when I load Windows it works normal. PLEASE HELP

:newbie:

Re: still not working(slow internet connection)
 

Can you pls provide more info?
This post is about name resolution problem ie. when you type http://www.google.com you can see on the bottom bar of your browser a message like "resolving host" (the message depends on the browser). for like half a minute and then finally the page loads.
Is this what you're experiencing?
What if you ping www.yahoo.com? what is the response time you get? Is it regular?
If you type the IP@ of a website rather then the hostname, does the page loads faster?
If you FTP a file from the net, does it goes fast? This is a good test because the problem we're talking about in this post affect the resolution of the ftp site's name, but once the connection is establish download is like lightening (well if you have a T1 it should be ;) )

its exactly what you said. As soon as the site comes up. its lightning fast, but getting past the resolving is the problem.

PLEASE HELP

Once the downoad connects its fine, once the ping resolves yahoo.com it pings fine, sometiems the ping does drop however to 51 or 81ms. I don't understand that as I'm on a T1 and through windows I NEVER get this.

Please help

How about trying to put those 2 lines:
alias ipv6 off
alias net-pf-10 off
before the "alias eth0...". Just for a quick try. Note that I'm totally unsure this'll help but it's only a 30sec job, worth trying.
Beside this, how is you DNS configuration? Can you post your /etc/resolv.conf file? And also the output of the following command:
Also one way to debug this kind of problem is to do the following.
Open 2 consols (one as root). On the root one, type the command
Note that if you get "command not found" you'll have to install tcpdump.
This command will display any DNS traffic flowing through you ethernet card.
Then on the other shell, type:
This will resolve google and what will be interesting is to see what tcpdump is outputting. When done hit ctrl+c and copy/past tcpdump output in a post so that I can see how it looks.
If the problem comes from a bad DNS config we'll probably get some usefull info out of this. If it's some kind of kernel bug well then too bad. By the way, what distro and kernel are you using? (to display your kernel version: "uname -r")

grep host output:

#hosts: db files nisplus nis dns
hosts: files nisplus nis dns

resolv.conf output:

search networkalliance.net
nameserver 208.254.27.x
nameserver 63.124.148.x

the x does have a last characters but as I'm from work I don't want to post that.. Does anyone know of any Better DNS Servers I could use such as MCI or ATT or something like that?

To find other DNS servers, it's easy. You can do it that way:

Then you can see what their DNS are (irddd1.mcilink.com & wspdd1.mcilink.com), this is not secret info. You will have to nslook them up to get the IPs (well here ==> 166.32.161.244 & 166.33.212.187).
If you want to give them a try, let us know if they work better :)

still no huge change.

jeickal, cheers, that works for me too!