Apple doing anonymous data exchange in Mac? I've realized today that my iMac is sending/receiving(mostly send) some anonymous data over the internet(almost 500MB today), I checked with Little Snitch and found these addresses are consuming data on my Mac:

p24-caldav-current.edge.icloud.apple-dns.net,
 p24-caldav.icloud.com,
 p24-ckdatabase-current.edge.icloud.apple-dns.net,
 p24-ckdatabase.icloud.com,
 p24-contacts-current.edge.icloud.apple-dns.net,
 p24-contacts.icloud.com, 
 p24-escrowproxy-current.edge.icloud.apple-dns.net,
 p24-escrowproxy.icloud.com, 
 p24-keyvalueservice-current.edge.icloud.apple-dns.net,
 p24-keyvalueservice.icloud.com

As soon as i blocked them out, My mac stopped eating traffic!

What are these and why would apple exchange such amount of data ?
I see this question is a year old, but I was just researching the same thing and thought I'd share my answer.  I have used Little Snitch for years, but only began seeing the connection alerts referred to by OP after I turned on iCloud Sync in System Preferences.  If you have this option selected, I can confirm that this traffic can be attributed to your files being backed up to iCloud Drive.  

If you always use the same network configuration and/or are not overly conscious about security and privacy, allowing and whitelisting those hosts and/or IP addresses is perfectly fine.  But if you're running software like Little Snitch, then one might infer that you are at least more conscious about your anonymity and security than the average user.  If you are reading this and nodding, then I would suggest creating a new "Profile" in Little Snitch.  Furthermore, if you have access to a VPN or proxy, activate the "APS" (Automatic Profile-Switching) feature. Profiles can be toggled manually, or automatically (when you switch networks), whenever one wishes to regulate network connections more strictly.  This is useful for many reasons.  Some may simply wish to cut down on bandwidth-hungry, resource-intensive background processes.  Others may wish to anonymise themselves from censors, ISPs, advertisers, data-miners, governments, or other parties that could tie you to your internet use by logging your traffic, IP and geolocation.

Until last year, I might have doubted that Apple's logs of iCloud, iTunes, and App Store traffic would be employed to tie users to unrelated internet traffic.  But these logs, willingly provided by Apple, proved instrumental to the arrest of alleged "Kickass Torrents" domain owner [1] [2].  So now whenever I am torrenting, I am have Little Snitch switch to a new profile specifically for my VPN.  For more details, here are a few ideas.