On Cisco ISR routers, for what purpose is the realm-cisco.pub public encryption key used?

On Cisco ISR routers, for what purpose is the realm-cisco.pub public encryption key used?
A . used for SSH server/client authentication and encryption
B . used to verify the digital signature of the IPS signature file
C . used to generate a persistent self-signed identity certificate for the ISR so administrators can authenticate the ISR when accessing it using Cisco Configuration Professional
D . used to enable asymmetric encryption on IPsec and SSL VPNs
E . used during the DH exchanges on IPsec VPNs

View Answer

Answer: B

Explanation:

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6634/prod_white_paper090 0aecd805c4ea8.html

Step 1: Downloading IOS IPS files

The first step is to download IOS IPS signature package files and public crypto key from Cisco.com.

Step 1.1: Download the required signature files from Cisco.com to your PC

• Location: http://tools.cisco.com/support/downloads/go/Model.x?mdfid=281442967&mdfLevel=Software%20 Family&treeName=Security&modelName=Cisco%20IOS%20Intrusion%20Prevention%20System %20Feature%20Software&treeMdfId=268438162

• Files to download:

IOS-Sxxx-CLI.pkg: Signature package – download the latest signature package. realm-cisco.pub.key.txt: Public Crypto key – this is the crypto key used by IOS IPS