Internet Recovery Mode - Error -2006F

Then you can do Network Recovery. Try doing this:

1. Resetting your Mac’s PRAM and NVRAM
2. Reset the System Management Controller (SMC)
3. Start the computer in Safe Mode, then restart normally. This is slower than a standard startup.
4. Repair the disk by booting the from the Recovery HD. Immediately after the chime hold down the Command and R keys until the Utility Menu appears. Choose Disk Utility and click on the Continue button. Select the indented (usually, Macintosh HD) volumeentry from the side list. Click on the First Aid button in the toolbar. Wait for the Done button to appear. Quit Disk Utility and returnto the Utility Menu. Restart the computer from the Apple Menu.

Clean Install of El Capitan or Sierra

1. Restart the computer. Immediately after the chime hold down the Command-Option-R keys until a globe appears.
2. The Utility Menu will appear in from 5-20 minutes. Be patient.
3. Select Disk Utility and click on the Continue button.
4. When Disk Utility loads select the drive (usually, the out-dented entry) from the side list.
5. Click on the Partition tab in Disk Utility's main window. A panel will drop down.
6. Set the partition scheme to GUID.
7. Set the Format type to Mac OS Extended (Journaled.)
8. Click on the Apply button, then click on the Done button when it activates.
9. Quit Disk Utility and return to the Utility Menu.
10. Select Reinstall OS X and click on the Continue button.

See if this gets things done.

And, exactly which model do you have? An iMac from 2016 or from 2006? We have no way of knowing. So for now I can only tell you that if your iMac is from Late 2011 or later then you can do Network Recovery. Otherwise, you cannot. The error message usually indicates your model cannot do a Network Recovery. It may also occur if you are trying to use a public network.