Cisco Cisco Web Security Appliance S170 Guía Del Usuario
Chapter 25 Configuring Network Settings
Configuring DNS Server(s)
25-30
Cisco IronPort AsyncOS 7.0 for Web User Guide
OL-23079-01
AsyncOS randomly chooses between the two servers at priority 0. If one of the
priority 0 servers is down, the other is used. If both priority 0 servers are down,
the priority 1 server (1.2.3.6) is used, and finally, the priority 2 (1.2.3.7) server.
priority 0 servers is down, the other is used. If both priority 0 servers are down,
the priority 1 server (1.2.3.6) is used, and finally, the priority 2 (1.2.3.7) server.
The timeout period is the same for both priority 0 servers, longer for the priority
1 server, and longer still for the priority 2 server.
1 server, and longer still for the priority 2 server.
DNS Alert
If an alert with the message “Failed to bootstrap the DNS cache” is generated
when an appliance is rebooted, it means that the system was unable to contact its
primary DNS servers. This can happen at boot time if the DNS subsystem comes
online before network connectivity is established. If this message appears at other
times, it could indicate network issues or that the DNS configuration is not
pointing to a valid server.
when an appliance is rebooted, it means that the system was unable to contact its
primary DNS servers. This can happen at boot time if the DNS subsystem comes
online before network connectivity is established. If this message appears at other
times, it could indicate network issues or that the DNS configuration is not
pointing to a valid server.
Clearing the DNS Cache
You can use the Clear DNS Cache button on Network > DNS page, or the
dnsflush
command to clear all information in the DNS cache when changes have
been made to your local DNS system. Using this command might cause a
temporary performance degradation while the cache is repopulated.
temporary performance degradation while the cache is repopulated.
Configuring DNS
To edit DNS Settings:
Step 1
Navigate to the Network > DNS page.
Step 2
Click Edit Settings. The Edit DNS page appears.
1
1.2.3.6
10
2
1.2.3.7
45
Table 25-5
Example of DNS Servers, Priorities, and Timeout Intervals
Priority
Server(s)
Timeout (seconds)