You can put iLink day tickets onto na DayLink card which don't show any zones at all. The newer iLink cards which are slowly being phased in (I've only seen them at Eurospar next to Botanic station), don't have any zone number on.
In 2017 I bought an iLink card online with a Zone 4 day ticket. It was posted to me in London, I then went to NI and used the ticket successfully. The card has been in a drawer ever since.
I have a planned trip to NI shortly. It looks like if I buy a ticket online, they will just post a new card to me, and there is no way to add it to my existing card or even see if my existing card still works. Is this right? Seems a bit of a waste.
I called Translink and they said there was no way to see if my old card was still active other than physically going to an office or machine in NI.
So I did order a new card, and it still had Zone 4 printed on it.
The new card plus day ticket cost £18.50 online.
When I got to Belfast I found that the old card from 2017 was still working, though it said its most recent transaction took place in March 2033!
It was only possible to buy Zone 4 tickets on both cards, not any other zone, so individual cards would be needed if wanting different zones. The Z4 day ticket price with an existing card is £17.50, which means they charged £1 for the card plus postage. I couldn't find this information on the translink website.
Also buses still have the "driver covid protection screen" up, which makes it really awkward to get your card to the reader, you have to twist your arm through the hole, some elderly people really struggle to do this, and you have to take a separate ticket too...
There were very frequent revenue protection / anti-social behaviour deterrence checks on the Belfast Glider buses into the late evening/night... but anyone without a ticket was just made to get off, and no attempts were made to stop people getting off as the RPIs boarded. Also, the RPIs had to scan my card twice every time as the first scan always said it was invalid, but they anticipated this.