I'd like a query executed that shows the duration of the outage

[Sandeep007]

Can anyone help me to write a Splunk query for when I have an outage I'd like a query executed that shows the duration of the outage.  If I check 5XX or 4XX errors, It will show some logs in  hour 5 or 10 mins period ex: I checked 500 errors 10pm to 11pm...  in that one hour, errors started from 10:15pm to 10:45pm , I want only period {10:15pm to 10:45pm } no need logs  .. for that How I need to write quarry 

[tscroggins]

@Sandeep007 

If you're looking for time ranges within 1-hour periods, you can use e.g. timechart:

sourcetype=access_common status=500
| timechart span=1h earliest(_time) as et latest(_time) as lt range(_time) as duration
| fieldformat et=strftime(et, "%F %T")
| fieldformat lt=strftime(lt, "%F %T")
| fieldformat duration=tostring(duration, "duration")