Schools say they will cope if systems go down during online end-of-year exams.
On Friday, some secondary schools were forced to abort a digital numeracy exam - typically sat in Year 10 - after an unforeseen number of students logged on.
Some were blocked for nearly 40 minutes to avoid overloading.
NCEA exams for Years 11 to 13 start tomorrow, and more than 76,000 students from around 400 schools are entered to sit one or more of their NCEA exams online.
PPTA acting president Chris Abercrombie said exam supervisors had a back-up plan.
"If there are any digital issues - something as simple as, if a students battery goes flat on their device, to a system issue - there's back-up there and a paper copy available."
A NZQA spokesperson said NCEA exams were different.
It was known in advance how many students would log in and at what time, and extra capacity could be put in place.