Cisco ASA Series Cli Configuration Manual page 515

Chapter 1 Configuring Basic Settings
On the ASA, the no service password-recovery command prevents you from entering ROMMON mode
with the configuration intact. When you enter ROMMON mode, the ASA prompts you to erase all Flash
file systems.Yyou cannot enter ROMMON mode without first performing this erasure. If you choose not
to erase the Flash file system, the ASA reloads. Because password recovery depends on using ROMMON
mode and maintaining the existing configuration, this erasure prevents you from recovering a password.
However, disabling password recovery prevents unauthorized users from viewing the configuration or
inserting different passwords. In this case, to restore the system to an operating state, load a new image
and a backup configuration file, if available.
The service password-recovery command appears in the configuration file for information only. When
you enter the command at the CLI prompt, the setting is saved in NVRAM. The only way to change the
setting is to enter the command at the CLI prompt. Loading a new configuration with a different version
of the command does not change the setting. If you disable password recovery when the ASA is
configured to ignore the startup configuration at startup (in preparation for password recovery), then the
ASA changes the setting to load the startup configuration as usual. If you use failover, and the standby
unit is configured to ignore the startup configuration, then the same change is made to the configuration
register when the no service password recovery command replicates to the standby unit.
Monitoring DNS Cache
The ASA provides a local cache of DNS information from external DNS queries that are sent for certain
clientless SSL VPN and certificate commands. Each DNS translation request is first looked for in the
local cache. If the local cache has the information, the resulting IP address is returned. If the local cache
can not resolve the request, a DNS query is sent to the various DNS servers that have been configured.
If an external DNS server resolves the request, the resulting IP address is stored in the local cache with
its corresponding hostname.
To monitor the DNS cache, enter the following command:
Command
show dns-hosts
Purpose
Show the DNS cache, which includes dynamically learned
entries from a DNS server as well as manually entered name
and IP addresses using the name command.
Cisco ASA Series CLI Configuration Guide
Monitoring DNS Cache
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