Amazon (like a lot of others) use several CDNs for redundancy. You can see from dig that it resolves to combinations of cloudfront, akamai, and (presumably, based on your reported experience) fastly.

  dig +short www.amazon.com
  tp.47cf2c8c9-frontier.amazon.com.
  d3ag4hukkh62yn.cloudfront.net.
  65.8.70.16

  dig +short www.amazon.co.uk
  tp.bfbdc3ca1-frontier.amazon.co.uk.
  dmv2chczz9u6u.cloudfront.net.
  13.224.0.89

  dig +short www.amazon.in
  tp.c95e7e602-frontier.amazon.in.
  d1elgm1ww0d6wo.cloudfront.net.
  13.224.9.30

  dig +short www.amazon.co.jp
  tp.4d5ad1d2b-frontier.amazon.co.jp.
  www.amazon.co.jp.edgekey.net.
  e15312.a.akamaiedge.net.
  104.71.134.162