5.6 Configuring the Default Image Using the IsDefault Key and Troubleshooting

Using the IsDefault key, an image can be marked as the default image for all the servers, and the Mac devices can boot to the image using the N or OPT+N Keys.

Format 

<key>IsEnabled</key>
<true or false/>

To enable an image, set the value to true.

<key>IsEnabled</key>
<true/>

To disable an image, set the value to false.

<key>IsEnabled</key>
<true or false/>

5.6.1 Understanding Various Scenarios for the Default Images

Scenario 1: If none of the images are marked as default, then the image with the highest BootImageId value will be considered as the server default image.

Scenario 2: If all the images are marked as default, then the image with the highest BootImageId value will be considered when a Mac client requests for the default image using the N or OPT+N key.

Scenario 3: If there are multiple default images with same image index, out of applicable images, the image with the highest BootImageId will be considered.

5.6.2 Understanding the BootImageId

Following are some of the examples that helps you to understand the BootImageId:

Example 1:

An image of NetInstall of macOS Mojave having index value 1, the BootImageId would be: 0x81000001

BootImageId: 0x81000001

  • Boot Image Attribute = 8100

  • Boot Image Index = 0001

Boot Image Attribute = 8100 (Binary = 1000 0001 0000 0000)

  • Image Type = Install (1000 = 0x1)

  • Kind = MacOS X (0001 = 0x01)

  • Reserved = 0000 0000

Example 2:

An image of NetRestore of macOS Mojave having index value 2, the BootImageId would be: 0x81000002

BootImageId: 0x81000002

  • Boot Image Attribute = 8100

  • Boot Image Index = 0002

Boot Image Attribute = 8100 (Binary = 1000 0001 0000 0000)

  • Image Type = Install (1000 = 0x1)

  • Kind = MacOS X (0001 = 0x01)

  • Reserved = 0000 0000

Example 3:

An image of NetBoot of macOS Mojave having index value 3, the BootImageId would be: 0x01000003

BootImageId: 0x01000003

  • Boot Image Attribute = 0100

  • Boot Image Index = 0003

Boot Image Attribute = 0100 (Binary = 0000 0001 0000 0000)

  • Image Type = Non-install (0000 = 0x0)

  • Kind = MacOS X (0001 = 0x1)

  • Reserved = 0000 0000

If all the above three images are marked as default, then the image having the highest BootImageId will be considered as the default. In this case, the NetRestore image of macOS Mojave with BootImageId 0x81000002 is considered as the default image.