What are api.smoot.apple.com and other hosts my iPhone is secretly talking to?
Regarding api.smoot.apple.com, from Hacker News. Note this is regarding Yosemite, but I would imagine it similarly applies to Mobile Safari on iOS, especially since the hostname is the same (emphasis mine):

There are two &quot;Spotlight Suggestions&quot;:

&quot;Spotlight Suggestions&quot; in Safari
&quot;Spotlight Suggestions&quot; in Spotlight

Both query the same servers, both use the same name, and both return the same information.
A reasonable person might believe that, having followed Apple's instructions for disabling &quot;Spotlight Suggestions&quot; (the Spotlight kind), they'd disabled &quot;Spotlight Suggestions&quot; (the Safari kind) -- especially if you didn't actually see any suggestions appear in Safari (I didn't!).
Mark Rowe, Safari developer at Apple: &quot;That’s probably a fair complaint.&quot; https://twitter.com/bdash/status/524005838743035904
...
The network query posted here is actually a search metrics POST, not a live search query, and it's used as metrics for local and remote search performance.