问题：

[多选]

Refer to the exhibit. Which two statements about the SDF Locations window of the IPS Rule wizard are true？（）

A . An HTTP SDF file location can be specified by clicking the Add button.
B . If all specified SDF locations fail to load， the signature file that is named default.sdf will be loaded.
C . The Autosave feature automatically saves the SDF alarms if the router crashes.
D . The Autosave feature is automatically enabled for the default built-in signature file.
E . The name of the built-in signature file is default.sdf.
F . The Use Built-In Signatures （as backup） check box is selected by default.