yum configuration for proxy server

[Sumeet Pal Singh]

Hi
I am behind a two proxy server, one requires authentication and is
fast, other slow but requires no authentication. Can someone tell me
how to configure yum to work with the first one. I am using FC4.
on doing 
[root at spsingh sumeet]# yum update

You have enabled checking of packages via GPG keys. This is a good thing.
However, you do not have any GPG public keys installed. You need to download
the keys for packages you wish to install and install them.
You can do that by running the command:
    rpm --import public.gpg.key


Alternatively you can specify the url to the key you would like to use
for a repository in the 'gpgkey' option in a repository section and yum
will install it for you.

For more information contact your distribution or package provider.

I tried it on the latter and tried to install keys using
[root at spsingh sumeet]# rpm --import
http://dag.wieers.com/packages/RPM-GPG-KEY.dag.txt
error: http://dag.wieers.com/packages/RPM-GPG-KEY.dag.txt: import read
failed(-1).
rpmk: url.c:103: XurlFree: Assertion `u && u->magic == 0xd00b1ed0' failed.
Aborted

Please help
Also, The second proxy is on ipv6