http://mirror.centos.org/centos/$major.$minor/os/$arch, doesn't work for Centos 7 (or 6, or 5)

D, [2014-08-01T14:41:13.820310 #3745] DEBUG -- : Starting task (total: 0): /usr/bin/wget --timeout=10 --tries=3 --no-check-certificate -nv -c "http://mirror.centos.org/centos/7./os/x86_64/images/pxeboot/vmlinuz" -O "/var/lib/tftpboot/boot/Centos7-7-x86_64-vmlinuz" 
D, [2014-08-01T14:41:13.914386 #3745] DEBUG -- : Starting task (total: 0): /usr/bin/wget --timeout=10 --tries=3 --no-check-certificate -nv -c "http://mirror.centos.org/centos/7./os/x86_64/images/pxeboot/initrd.img" -O "/var/lib/tftpboot/boot/Centos7-7-x86_64-initrd.img" 
E, [2014-08-01T14:41:14.053902 #3745] ERROR -- : [4851] http://mirror.centos.org/centos/7./os/x86_64/images/pxeboot/vmlinuz:

E, [2014-08-01T14:41:14.054012 #3745] ERROR -- : [4851] 2014-08-01 14:41:14 ERROR 404: Not Found.

E, [2014-08-01T14:41:14.066278 #3745] ERROR -- : [5334] http://mirror.centos.org/centos/7./os/x86_64/images/pxeboot/initrd.img:

E, [2014-08-01T14:41:14.066342 #3745] ERROR -- : [5334] 2014-08-01 14:41:14 ERROR 404: Not Found.

So created a new Centos 7 mirror with:
http://mirror.centos.org/centos/$major/os/$arch

But there must be some cleaner way.