Sunday, March 11, 2012
Here is what Facebook says in its recent Registration Statement to the SEC (here):
"Our metrics are also affected by applications on certain mobile devices that automatically contact our servers for regular updates with no user action involved, and this activity can cause our system to count the user associated with such a device as an active user on the day such contact occurs. We estimate that less than 5% of our estimated worldwide DAUs [daily active users] as of December 31, 2011 and 2010 resulted from this type of automatic mobile activity, and that this type of activity had a substantially smaller effect on our estimate of worldwide MAUs [monthly active users] and mobile MAUs. The impact of this automatic activity on our metrics varies by geography because mobile usage varies in different regions of the world".
This may not be significant in terms of traffic, but joins the general phenomena of "signaling" /"keep-alive" traffic, in different communication layers. However, it does impose load on mobile networks, for example in the number of concurrent connections/PDP contexts etc - with questionable value to the user.
Another example at the application layer: VoIP (see "NTT Explains Outage and its $1.5B Corrective Action" - here)