up2date's yum-mirror directive question

[Jorge Fábregas]

Hello everyone,

I have these 2 lines on my /etc/sysconfig/rhn/sources:
yum updates http://mirror.hiwaay.net/redhat/fedora/linux/core/updates/3
yum-mirror updates file:/etc/sysconfig/rhn/mirrors

This is the content of mirrors:
http://mirrors.xmission.com/fedora/core/updates/3/i386/

I've been running up2date (from command-line to see output) for more than 30 
times. In all of them, up2date is using the mirror site. It is never using 
the main (hiwaay) site. I thought that up2date decided which site to use 
randomly (whether the main one or mirros) but once I started using the 
yum-mirror directive...it is always using the mirrors. Is this normal? If so, 
why then have the main yum channel-name main-site-url line?
 
Thanks in advance,
Jorge