While many of us are focused on the newest and newly released ZenFone 2 smartphones from Asus, the Taiwanese company just started rolling out OTA (over-the-air) Android 5.0 Lollipop updates for the other ZenFone devices that were released last year, the ZenFone 4, 5 and 6. Good thing the rumored delay didn't pan out.
So you if you own one of these smartphones, you may now start checking the update availability on your device to see if the OTA is ready to download. It is also important to note that Asus is releasing the over the air software update in "phase" mode which means some of you may still not see the update yet ready, but don't worry you can still do it yourself by going to the Asus forum sites by manually downloading the Android Lollipop to your device. See source links below.
Source 2: ZenFone 4 ( A400CG/CXG )
Source 1: ZenFone 5 ( A500CG / A501CG )
Source 3: ZenFone 6 ( A600CG / A601CG )