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When you use a predefined attribute, you can modify it and change its name, but you cannot change the type of data it accepts. You can also delete predefined attributes that you do not use. All predefined attributes accept text strings. You can define other settings though, as described in Modifying Extensible Attributes. You can also create your own extensible attributes, as described in Adding Extensible Attributes.
For example, you can configure the predefined attribute Site for fixed addresses and hosts, and define a new attribute Department for admin groups.
When you configure an extensible attribute, you can specify the following:
- The type of data that admins enter, such as text strings, integers, or email addresses. You can also restrict admins to a list of values.
- Whether admins can enter multiple values
- A default value
- Whether the attribute is required
- Whether the attribute is inheritable
- The objects associated with the attribute, such as admin groups, DNS views, or DHCP networks.
- Whether the appliance makes an entry in the audit log each time an object with the attribute is added or modified.
Activities such as additions, modifications, and deletions of inheritable extensible attributes, are recorded in the audit log. For information about how to use the audit log, see Using the Audit Log.
Figure 8.5 illustrates a network with different device types. Each device is represented as a host in the NIOS appliance database. You can configure Device Type, Location and Owner as required attributes for hosts. Then when admins add hosts, they will be required to enter values for these attributes in the Extensible Attributes tab of the Add Host wizard.
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| Inheritance | State Description |
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| Inherited | The extensible attribute inherits its value from the parent. You cannot edit the value of an attribute when the inheritance state is set to Inherited. You can change the state to Overridden and then change the value of the attribute or change the state to Not Inherited to remove the inherited value. |
| Overridden | The extensible attribute overrides the value inherited from the parent. You can change the state to Inherited and restore the original inherited value or change the state to Not Inherited and remove the inherited value. |
| Not Inherited | The extensible attribute can inherit its value from the parent, but the attribute does not exist on the descendant. You can change the state to Inherited and restore the original inherited value or change the state to Overridden and change the value of the attribute. Note that when the state of an inheritable extensible attribute is Not Inherited, the corresponding attribute will not be added as a new extensible attribute for objects that are currently not inheriting this extensible attribute. |
| No Parent | The inheritance state is set to No Parent when an object has a parent, but the parent does not have an extensible attribute or the parent's extensible attribute is set to Not Inherited. |
| Disabled | Extensible attribute inheritance is not enabled for the attribute. |
| No Change | The extensible attributes of the selected objects do not have the same inheritance state for all objects. This state allows you to retain the current state on the selected objects. Note that this state is only seen in the Multi-object Extensible Attributes editor. |
When you add an inheritable extensible attribute to an object, if there are descendants of this object the Descendant Actions dialog box is displayed which will provide options for the descendants. Following is a summary of these options:
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When values are inherited by a descendant, the inheritance state of the inherited extensible attribute is displayed as Inherited. You can select Overridden and specify a new value or select Inherited to retain the same value as the parent. If you select Not Inherited, the extensible attribute and its value will not be inherited. The inherited value will have a strike-through and you cannot edit the value when the state is set to Not Inherited.
In addition to the attribute values, the Value column of an inheritable extensible attribute also displays the name of the source and the object type of the extensible attribute. For example, a Network Container has a descendant, Network, which inherits an extensible attribute value from Network Container and Network has a descendant, Fixed Address that inherits the same extensible attribute value. In this case, Fixed Address shows Network Container as the source.
The following table displays various inheritance states and corresponding changes to source and object types that are displayed in the Value column of an extensible attribute.
| Inheritance State | Source and Object Type in the Value Column |
|---|---|
| If an extensible attribute is a native attribute (an object which is at the top of the inheritance chain, or does not have ancestors), | Source is not displayed in the Value column. This column will not display the source details, if none of the selected objects support inheritance. |
| If the state of an extensible attribute is set to Inherited, | then the Source and object is displayed. You cannot change the value of the extensible attribute. |
| If the state of an extensible attribute is set to Overridden or Not Inherited, | then the Source will have a strike-through. You can change the state of such extensible attributes. You cannot change the value of the extensible attribute when the inheritance state is set to Not Inherited. |
To modify the value and inheritance state of an inheritable extensible attribute:
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