[CentOS] mirrors.centos.org DNS problems?

>From various place I can't resolve the name; from others it works fine

eg
 on my FIOS line (96.234.66.*): fail
 from Panix internet (166.84.67.*): success
                     (166.84.5.*): success
 from bt.net (194.72.6.*): fail
 from he.net (65.19.175.*): fail
 from AShosting.nl (81.171.86.*): success

-- 

rgds
Stephen