Cisco ASA 5505 Configuration Manual page 300

Guidelines and Limitations
Guidelines and Limitations
Failover Guidelines
Supports Active/Active and Active/Standby failover.
Firewall Mode Guidelines
Supported in routed firewall mode.
Context Mode Guidelines
Supported in single and multiple context modes.
Supported in transparent mode for the DNS Client pane.
IPv6 Guidelines
Supports IPv6.
Configuring Dynamic DNS
Dynamic DNS provides address and domain name mapping so that hosts can find each other, even
though their DHCP-assigned IP addresses change frequently. The DDNS name and address mapping are
stored on the DHCP server in two resource records: the A RR includes the name-to-IP address mapping,
while the PTR RR maps addresses to names. Of the two methods for performing DDNS updates—the
IETF standard defined by RFC 2136 and a generic HTTP method—the adaptive security appliance
supports the IETF method in this release.
The Dynamic DNS pane shows the configured DDNS update methods and the interfaces that have been
configured for DDNS. By automatically recording the association between assigned addresses and
hostnames at pre-defined intervals, DDNS allows frequently changing address-hostname associations to
be updated regularly. Mobile hosts, for example, can then move freely on a network without user or
administrator intervention.
To configure dynamic DNS client settings for updating the DNS server, perform the following steps:
In the ASDM main application window, choose Configuration > Device Management > DNS >
Step 1
Dynamic DNS.
Click Add to display the Add Dynamic DNS Update Method dialog box.
Step 2
Enter the name for the DDNS update method.
Step 3
Specify the update interval between DNS update attempts configured for the update method in days,
Step 4
hours, minutes, and seconds.
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These units are additive. That is, if you enter 0 days, 0 hours, 5 minutes and 15 seconds, the update
method tries an update every 5 minutes and 15 seconds for as long as the method is active.
To store server resource record updates that the DNS client updates, choose one of the following options:
Step 5
Cisco ASA 5500 Series Configuration Guide using ASDM
11-2
Choose the number of days between update attempts from 0 to 364.
Choose the number of hours (in whole numbers) between update attempts from 0 to 23.
Choose the number of minutes (in whole numbers) between update attempts from 0 to 59.
Choose the number of seconds (in whole numbers) between update attempts from 0 to 59.
Chapter 11 Configuring Dynamic DNS
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