Do you have an http cache between NethServer and the mirrors?
Here I see:
[root@nscom ~]# yum repolist
Loaded plugins: changelog, fastestmirror, nethserver_events, presto
Determining fastest mirrors
* centos-base: centos.muzzy.it
* centos-updates: ba.mirror.garr.it
Including mirror: mirror.nethserver.org
* nethserver-base: mirror.nethserver.org
Including mirror: mirror.nethserver.org
* nethserver-updates: mirror.nethserver.org
centos-base | 3.7 kB 00:00
centos-base/primary_db | 4.6 MB 00:01
centos-updates | 3.4 kB 00:00
centos-updates/primary_db | 3.2 MB 00:00
nethserver-base | 3.7 kB 00:00
nethserver-base/primary_db | 436 kB 00:00
nethserver-updates | 4.1 kB 00:00
nethserver-updates/primary_db | 129 kB 00:00
repo id repo name status
centos-base CentOS-6 Base 6,575
centos-updates CentOS-6 Updates 954
nethserver-base NethServer 6.7 base 446
nethserver-updates NethServer 6.7 updates 70
repolist: 8,045
[root@nscom ~]# yum list | grep pulled
nethserver-pulledpork.noarch 1.0.2-1.ns6 @nethserver-updates
pulledpork.noarch 0.7.0-2 @nethserver-base