If you can ping but almost nothing else (including yum) works

[scottro]

I'll make this sticky till it's fixed.

If you have a 64 bit system, and install wine, chromium, or possibly some other programs, you may suddenly find that although pinging by hostname and graphical browsers work, most other things, such as ssh by hostname, and even yum, are suddenly unable to resolve DNS.

This is caused by some packages that are 32 bit only, such as the abovementioned wine and chromium, pull in a package called nss-mdns, but pull in the 32 bit version.

The package rudely overwrites your nsswitch.conf, adding a line to break most things.

One fix is to edit /etc/nsswitch.conf. You will see a line

hosts: files mdns4_minimal [NOTFOUND=return] dns

Put a # in front of the line to comment it out.

Now, things will work again.

Now that yum is working do

yum -y install nss-mdns

This will install the 64 bit version of the package. Once you have the 64 bit version installed, it will probably once again overwrite nsswitch.conf, re-adding the offending line, but that's fine--if you have the 64 bit version it will work.

If for some reason, it doesn't rewrite the file again, as a reader pointed out, be sure to uncomment the line again by removing the # sign.


It is a known bug, so will hopefully be fixed in the near future.

[leigh123linux]

After editing it try

su
chmod -w /etc/nsswitch.conf

[scottro]

Hrrm--wouldn't you want to let it, be re-written again by the 64 bit version? (Or do you mean edit it after installing the 64 bit version?)


Or is that the whole line is simply not a good idea?

Thanks.

[scottro]

An additional thought--untested, but recommended to me by someone I respect. Rather than comment out the line, one might be able to fix it by simply changing the order so that rather than it reading

hosts: files mdns4_minimal [NOTFOUND=return] dns


It reads

hosts: files dns mdns4_minimal [NOTFOUND=return]


One might also be able to fix it by just removing the NOTFOUND=return. I haven't tested either solution, and actually, commenting it out and then installing the 64 bit seems easiest to me, but thought I'd offer those other suggestions.