I asked Viasat several months ago whether overhead data was being added to actual usage. I also asked Viasat at that time about the accuracy of the LNFZ starting/ending times. I never heard back from Viasat on these questions. However, my data so far indicates to me that he answer to the overhead question is none. The answer to the LNFZ question is that it is accurately measured.
My plan rolled over two nights ago at midnight, Sept 4. Viasat charged me 0.3 GB for the period encompassing midnight Sept 4 until 7:00 AM Sept 5.
My Asus router indicated that 1.35 GB flowed externally through the router during this same time. I scheduled a LNFZ download from 3:05 AM until 6:00 AM on Sept 5. The router indicates that the data transmitted during this LNFZ was 1.05 GB. When the data for the LNFZ is subtracted out, the difference between these two numbers is 0.3 GB, which agrees precisely with Viasat’s data charge.
Therefore, from midnight September 4 until 7:00 AM September 5, Viasat charged data to me as it said it would. The LNFZ data was correctly handled and there appears to be no additional overhead data charged to me.It is premature to conclude much from such a small sample size. Nevertheless, if this accuracy continues for a whole month then I will conclude that Viasat is treating me honestly regarding data usage by me.