Cisco ASA 5505 - Manual (Page 356)

12-2
Cisco ASA 5500 Series Configuration Guide using the CLI
Chapter 12 Configuring Dynamic DNS
Licensing Requirements for DDNS
Licensing Requirements for DDNS
The following table shows the licensing requirements for DDNS:
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 DDNS
This section describes examples for configuring the ASA to support Dynamic DNS. DDNS update
integrates DNS with DHCP. The two protocols are complementary—DHCP centralizes and automates
IP address allocation, while dynamic DNS update automatically records the association between
assigned addresses and hostnames. When you use DHCP and dynamic DNS update, this configures a
host automatically for network access whenever it attaches to the IP network. You can locate and reach
the host using its permanent, unique DNS hostname. Mobile hosts, for example, can move freely without
user or administrator intervention.
DDNS 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 is held on the
DHCP server in two resource records: the A RR includes the name-to I- 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 ASA supports the IETF method in this release.
The two most common DDNS update configurations are the following:
• The DHCP client updates the A RR, while the DHCP server updates the PTR RR.
• The DHCP server updates both the A RR and PTR RR.
Model License Requirement
All models Base License.