Are you sure you’re really connecting to swcdn.apple.com? DNS poisoning attacks are common these days. Do you have the actual IP address you connected to?
Here is what I get:
> swcdn.apple.com
Server: google-public-dns-a.google.com
Address: 8.8.8.8
Non-authoritative answer:
Name: swcdn.g.aaplimg.com
Address: 17.253.15.202
Aliases: swcdn.apple.com
swcdn.apple.com.akadns.net
I am using the Google public DNS servers, so that should be a clean lookup.