I run 
$ [root@localhost rooster]# journalctl -u packagekit -f -n 5000
in fedora 
[root@localhost rooster]# cat /etc/redhat-release 
Fedora release 22 (Twenty Two)
and it results something like below lines:
Jul 21 06:54:28 localhost.localdomain PackageKit[18871]: uid 1000 is trying to obtain org.freedesktop.packagekit.system-sources-refresh auth (only_trusted:0)
Jul 21 06:54:28 localhost.localdomain PackageKit[18871]: uid 1000 obtained auth for org.freedesktop.packagekit.system-sources-refresh
Jul 21 07:36:45 localhost.localdomain PackageKit[18871]: refresh-cache transaction /345_edadcabc from uid 1000 finished with success after 2536929ms
Jul 21 07:36:45 localhost.localdomain PackageKit[18871]: get-updates transaction /346_aaeccddc from uid 1000 finished with success after 555ms
Jul 21 07:36:45 localhost.localdomain PackageKit[18871]: new update-packages transaction /347_eacacecc scheduled from uid 1000
Jul 21 07:36:48 localhost.localdomain PackageKit[18871]: update-packages transaction /347_eacacecc from uid 1000 finished with cancelled-priority after 2594ms
Jul 21 07:36:48 localhost.localdomain PackageKit[18871]: resolve transaction /348_caabddad from uid 1000 finished with success after 143ms
Jul 21 07:36:48 localhost.localdomain PackageKit[18871]: resolve transaction /349_aabcaabc from uid 1000 finished with success after 83ms
Jul 21 07:36:48 localhost.localdomain PackageKit[18871]: resolve transaction /350_dbadaaeb from uid 1000 finished with success after 31ms
Jul 21 07:36:50 localhost.localdomain PackageKit[18871]: new update-packages transaction /351_bebbaccb scheduled from uid 1000
Jul 21 09:27:31 localhost.localdomain PackageKit[18871]: update-packages transaction /351_bebbaccb from uid 1000 finished with success after 6640574ms
Jul 21 09:27:35 localhost.localdomain PackageKit[18871]: resolve transaction /352_cababcaa from uid 1000 finished with success after 30ms
Jul 21 09:27:35 localhost.localdomain PackageKit[18871]: resolve transaction /353_ccabcecc from uid 1000 finished with success after 81ms
Jul 21 09:27:35 localhost.localdomain PackageKit[18871]: resolve transaction /354_caddccdb from uid 1000 finished with success after 30ms
Jul 21 09:27:35 localhost.localdomain PackageKit[18871]: resolve transaction /355_ddaacaea from uid 1000 finished with success after 278ms
Jul 21 09:27:37 localhost.localdomain PackageKit[18871]: get-update-detail transaction /356_dabbaeed from uid 1000 finished with success after 1611ms


It has very suspicious and unusual behavior to use network bandwidth. For example in 10 days it downloads over 2GB from net!!! regardless of dnf or yum updates...