$ dig ns eu-west-1.amazonaws.com +short
ns3.p31.dynect.net.
ns1.p31.dynect.net.
ns4.p31.dynect.net.
ns2.p31.dynect.net.
$ dig ns eu-west-2.amazonaws.com +short
u6.amazonaws.com.
u5.amazonaws.com.
u2.amazonaws.com.
u4.amazonaws.com.
u1.amazonaws.com.
u3.amazonaws.com.
pdns1.ultradns.net.
pdns3.ultradns.org.
pdns5.ultradns.info.
ns2.p31.dynect.net.
ns1.p31.dynect.net.
ns4.p31.dynect.net.
ns3.p31.dynect.net.
Edit: Seems its hitting their anycasted ranges and taking everything off with it. Even their status page appears to be offline from here.