In order to conserve the limited bandwidth available, ISO images are not downloadable from mirror.centos.org

http://mirror.vcu.edu/pub/gnu_linux/centos-altarch/7.9.2009/isos/ppc64/

http://mirror.dal.nexril.net/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.xtom.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.genesishosting.com/centos-altarch/7.9.2009/isos/ppc64/
http://repos.eggycrew.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.ocf.berkeley.edu/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.chpc.utah.edu/pub/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.facebook.net/centos-altarch/7.9.2009/isos/ppc64/
http://ftp.osuosl.org/pub/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.lax.genesisadaptive.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.math.princeton.edu/pub/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.atl.genesisadaptive.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.vacares.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.genesisadaptive.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.pit.teraswitch.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.esecuredata.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.0xem.ma/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.calgah.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.12z.eu/pub/linux/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.cedia.org.ec/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.dotsrc.org/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.xtom.nl/centos-altarch/7.9.2009/isos/ppc64/
http://mirror1.hs-esslingen.de/pub/Mirrors/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.mivocloud.com/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.repository.id/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.coreix.net/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.lagoon.nc/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.tuna.tsinghua.edu.cn/centos-altarch/7.9.2009/isos/ppc64/
http://mirror.truenetwork.ru/centos-altarch/7.9.2009/isos/ppc64/
http://mirrors.bfsu.edu.cn/centos-altarch/7.9.2009/isos/ppc64/
+ others, see the full list of mirrors: https://www.centos.org/download/altarch-mirrors/

Mirrors verified Wed Oct 27 11:11:49 2021 UTC

You can also download the ISO images using bittorrent, a peer-to-peer file sharing protocol. The .torrent files can be found from CentOS mirrors. Various bittorrent clients are available, including (in no particular order of preference): utorrent, vuze (Azureus), BitTorrent, Deluge, ctorrent, ktorrent, rtorrent and transmission. Packaged copies of various torrent clients for CentOS can be found in the repositories listed in the following wiki article: https://wiki.centos.org/AdditionalResources/Repositories