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Re: F10, NetworkManager, and intermittent dns



McGuffey, David C. wrote:
A couple of weeks back I did a fresh install of F10, blowing away F7.
Got F10 up and running, did an update and then converted to static IP
addressing.  Everything went downhill from there.  Could only get on the
network about 1 out of 10 attempts. This is on a wired network.

Did some research and discovered on an Ubuntu forum a recommendation to
pin the MAC address to an IP address in the dhcpd configuration of the
IPS firewall/switch device, and then go back to dynamic addressing.

Did that, and did a complete fresh install of F10 with dynamic
addressing.  Data held by NM seems to be correct. I can ping all the
devices on the 192.168.1.0 network, and can use cups to print to two
printers on that network.  I got to a mirror site and downloaded the F10
updates and applied them. So far, so good.
Most of the time, I can browse out and get Evolution to upload/download
e-mail.  I say most of the time, because after a while, the box starts
getting dns errors (failure to resolve address).  It is intermittent,
and has been driving me nuts.

I finally discovered a pattern.  After a reboot, the first user can log
in and everything works.  That user can log out and a second user log in
and everything works. This can be repeated until the cows come home.
However, if either of those users let the screensaver kick off, dns
disappears for all users until a reboot. The Windoze XP Pro side of this
box doesn't skip a beat. Two other Windoze laptops (one XP and one
Vista) have no problems, and neither did a guest laptop on the wireless
side of the ISP firewall/switch, so I don't think there is an issue with
the ISP firewall/switch.
This NM stuff is new to me.  The old way worked and worked and
worked...better than the Energizer Bunny.  This NM tool, in my opinion,
is not ready for big time, and there is not enough documentation so
someone can come back and yell at me to rtfm.

Tonight I'm going to install tshark and see what I can discover in the
network traffic.

Where do I start?
Start by booting and saving a copy of /etc/resolv.conf. Then let the screensaver kick in, resume, and look at the resolv.conf file again. Other things to save and check are (a) "netstat -rn" or your favorite similar command, (b) "ifconfig" to see if the network is working. From the original resolv.conf file you can see the nameserver address(es) and then see if you can reach them after DNS fails, assuming the resolv.conf file isn't getting hosed. If you ping they may not respond (mine don't), but if you get "no route to host" you have something else wrong.

Does your screensaver config kick the system to low power mode, or suspend it, or do anything but change the screen display?

--
Bill Davidsen <davidsen tmr com>
  "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot


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