In order to conserve the limited bandwidth available, ISO images are not downloadable from mirror.centos.org
The following mirrors should have the ISO images available:
http://centos-distro.cavecreek.net/centos/8.1.1911/isos/aarch64/
http://mirrors.usinternet.com/centos/8.1.1911/isos/aarch64/
http://mirror.umd.edu/centos/8.1.1911/isos/aarch64/
http://repo.miserver.it.umich.edu/centos/8.1.1911/isos/aarch64/
http://mirror.grid.uchicago.edu/pub/linux/centos/8.1.1911/isos/aarch64/
http://repos.dfw.quadranet.com/centos/8.1.1911/isos/aarch64/
http://mirror.linux.duke.edu/pub/centos/8.1.1911/isos/aarch64/
http://repo1.ash.innoscale.net/centos/8.1.1911/isos/aarch64/
http://sjc.edge.kernel.org/centos/8.1.1911/isos/aarch64/
http://centos4.zswap.net/8.1.1911/isos/aarch64/
http://mirror.san.fastserv.com/pub/linux/centos/8.1.1911/isos/aarch64/
http://ftp.ussg.iu.edu/linux/centos/8.1.1911/isos/aarch64/
http://mirror.mia11.us.leaseweb.net/centos/8.1.1911/isos/aarch64/
http://yum.tamu.edu/centos/8.1.1911/isos/aarch64/
http://ftp.osuosl.org/pub/centos/8.1.1911/isos/aarch64/
http://mirrors.codec-cluster.org/centos/8.1.1911/isos/aarch64/
http://mirror.math.princeton.edu/pub/centos/8.1.1911/isos/aarch64/
http://mirrors.mit.edu/centos/8.1.1911/isos/aarch64/
http://repos.hou.layerhost.com/centos/8.1.1911/isos/aarch64/
http://mirror.keystealth.org/centos/8.1.1911/isos/aarch64/
http://distro.ibiblio.org/centos/8.1.1911/isos/aarch64/
http://mirror.xrepo.net/centos/8.1.1911/isos/aarch64/
http://mirror.hostduplex.com/centos/8.1.1911/isos/aarch64/
http://repos.lax.layerhost.com/centos/8.1.1911/isos/aarch64/
http://mirrors.oit.uci.edu/centos/8.1.1911/isos/aarch64/
http://linux.cc.lehigh.edu/centos/8.1.1911/isos/aarch64/
http://mirror.chpc.utah.edu/pub/centos/8.1.1911/isos/aarch64/
http://mirrors.lug.mtu.edu/centos/8.1.1911/isos/aarch64/
http://mirrors.cmich.edu/centos/8.1.1911/isos/aarch64/
http://mirrors.umflint.edu/CentOS/8.1.1911/isos/aarch64/
+ others, see the full list of mirrors: https://www.centos.org/download/mirrors/
Mirrors verified Mon Jun 15 05:34:26 2020 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
The following mirrors should have the ISO images available:
http://centos-distro.cavecreek.net/centos/8.1.1911/isos/aarch64/
http://mirrors.usinternet.com/centos/8.1.1911/isos/aarch64/
http://mirror.umd.edu/centos/8.1.1911/isos/aarch64/
http://repo.miserver.it.umich.edu/centos/8.1.1911/isos/aarch64/
http://mirror.grid.uchicago.edu/pub/linux/centos/8.1.1911/isos/aarch64/
http://repos.dfw.quadranet.com/centos/8.1.1911/isos/aarch64/
http://mirror.linux.duke.edu/pub/centos/8.1.1911/isos/aarch64/
http://repo1.ash.innoscale.net/centos/8.1.1911/isos/aarch64/
http://sjc.edge.kernel.org/centos/8.1.1911/isos/aarch64/
http://centos4.zswap.net/8.1.1911/isos/aarch64/
http://mirror.san.fastserv.com/pub/linux/centos/8.1.1911/isos/aarch64/
http://ftp.ussg.iu.edu/linux/centos/8.1.1911/isos/aarch64/
http://mirror.mia11.us.leaseweb.net/centos/8.1.1911/isos/aarch64/
http://yum.tamu.edu/centos/8.1.1911/isos/aarch64/
http://ftp.osuosl.org/pub/centos/8.1.1911/isos/aarch64/
http://mirrors.codec-cluster.org/centos/8.1.1911/isos/aarch64/
http://mirror.math.princeton.edu/pub/centos/8.1.1911/isos/aarch64/
http://mirrors.mit.edu/centos/8.1.1911/isos/aarch64/
http://repos.hou.layerhost.com/centos/8.1.1911/isos/aarch64/
http://mirror.keystealth.org/centos/8.1.1911/isos/aarch64/
http://distro.ibiblio.org/centos/8.1.1911/isos/aarch64/
http://mirror.xrepo.net/centos/8.1.1911/isos/aarch64/
http://mirror.hostduplex.com/centos/8.1.1911/isos/aarch64/
http://repos.lax.layerhost.com/centos/8.1.1911/isos/aarch64/
http://mirrors.oit.uci.edu/centos/8.1.1911/isos/aarch64/
http://linux.cc.lehigh.edu/centos/8.1.1911/isos/aarch64/
http://mirror.chpc.utah.edu/pub/centos/8.1.1911/isos/aarch64/
http://mirrors.lug.mtu.edu/centos/8.1.1911/isos/aarch64/
http://mirrors.cmich.edu/centos/8.1.1911/isos/aarch64/
http://mirrors.umflint.edu/CentOS/8.1.1911/isos/aarch64/
+ others, see the full list of mirrors: https://www.centos.org/download/mirrors/
Mirrors verified Mon Jun 15 05:34:26 2020 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