# Defining Alias elements

Alias elements represent different IP addresses depending on the engine on which they are used.

Alias elements are like variables: they can be given different IP address values in the policy depending on the engine on which the policy is installed. This makes it possible to create rules that are valid on several engines without including all IP addresses in the policies of all elements. Alias elements are especially useful in Template Policies.
Tip: You can view the IP addresses that the Alias represents in the policy of each component: in a policy, select More actions > Network Details. Then select a component from the list that is added to the toolbar.

Some of the default system Aliases always receive their values directly from other parts of each engine’s configuration and cannot be edited. These Aliases start with two $$ symbols. There are also some default Aliases that either do not receive any value without your action, or allow you to add to and change the default values. These Aliases start with one $ symbol, as do all Alias elements you create yourself.

## Alias Properties dialog box

Use this dialog box to define alias properties. Aliases are like variables: they can be given different IP address values in the policy depending on the engine on which the policy is installed.

Option | Definition
--- | ---
Name | Specifies the alias name in the SMC. Used, for example, to resolve IP addresses to names in the logs.
Category (Optional) | Categories allow you to flexibly filter your SMC Client view.
Select | Opens the Category Selection for New Element dialog box.
Comment (Optional) | An optional comment for your own reference.
Default Value (Optional) | The value that is used when the policy is installed on a component that does not have a more specific value for the Alias. If there is no default value, falling back to the default translation returns an empty value. If the Alias is the only element in the rule cell, the rule is invalid and ignored when the policy is installed (a warning is displayed if this happens).
Edit Default Value | Opens the Alias Value Properties dialog box.
Component-Specific Values (Optional) | The values that the Alias is replaced with when used in the policies of the components listed. If there is no specific translation value for a component, the default value is used instead.
Cluster | The list of components for the selected Alias.
Translation Value | Shows the translation value assigned to the component.
Edit Translation Value | Opens the Alias Value Properties dialog box for the selected component.