Labels are generally not shown for all the dataPoints & the dataPoints may be rendered beyond the last dataPoint as well. This is because axis labels are rendered with fixed interval.
The plot in your case might be extending beyond the label 6-11-17 as there might be a dataPoint beyond it with difference in some hours. If you are still facing the issue, kindly create a JSFiddle reproducing the issue and share it with us so that we can look into it and help you out.
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Suyash Singh
Team CanvasJS