The mistake is in the image 15 of 16. When ISP 4 requests the datacenter IP, it gets back “datacenter IP 4” but that datacenter doesn’t exist. I believe it was meant to be “datacenter IP 1” as per the description below the image.
You are right – the slides 14 and 15 should have “Datacenter 1 IP” instead of “Datacenter 4 IP.” We have now updated the slides as per your suggestion.
Thank you for improving the quality of our content.