Problem with a circuit that has only 2 outlets, one is fed from breaker and that one feeds a 2nd outlet, 2nd is not working anymore
If I read your question correctly you are getting 120 V hot to ground but not 120 V hot to neutral. That sounds like the neutral is broken or there is a poor connection of the ongoing neutral at the first or second receptacle. 

You have a voltmeter. Does it have a resistance function (ohms)?  If so you can check to see if the connection is broken between the two receptacles.

Turn off the breaker. Plug in a long extension cord sufficient to reach from the front porch receptacle all the way to the back receptacle (either through the house or around).

Test the resistance between the neutral in the cord and the neutral in the back receptacle. The neutral is the longer slot.

EDIT

If the neutral path is interrupted, you should see a high resistance hundreds or thousands of ohms. You can also check the resistance between the hot in the plug and the hot in the receptacle (shorter slots). Since you report you are getting 120 V hot to gnd, you should see a low resistance there (0.1 ohm or so). Be sure the breaker is off before connecting the meter in the resistance mode to any hots.