From the status page:

archlinux.org currently only available via ipv6 due to DDoS

Our main website is currently under attack which causes is to only be available via IPv6. As we need help from our hosting provider due to the nature of the attack and support times are rather limited over the holidays this could take a while to resolve. Aside from that: Merry Christmas to everyone but the attackers (if you happen to celebrate it) :)