Filter
Top Products
6-15
Cisco ASA Series Firewall ASDM Configuration Guide
Chapter 6 Configuring NAT (ASA 8.2 and Earlier)
NAT Overview
When an inside host sends a DNS request for the address of ftp.cisco.com, the DNS server replies with
the mapped address (209.165.201.10). The ASA refers to the static statement for the inside server and
translates the address inside the DNS reply to 10.1.3.14. If you do not enable DNS reply modification,
then the inside host attempts to send traffic to 209.165.201.10 instead of accessing ftp.cisco.com
directly.
Figure 6-12 DNS Reply Modification
Note If a user on a different network (for example, DMZ) also requests the IP address for ftp.cisco.com from
the outside DNS server, then the IP address in the DNS reply is also modified for this user, even though
the user is not on the Inside interface referenced by the static rule.
DNS Server
Outside
Inside
User
130021
1
2
3
4
5
DNS Reply Modification
209.165.201.10 10.1.3.14
DNS Reply
209.165.201.10
DNS Reply
10.1.3.14
DNS Query
ftp.cisco.com?
FTP Request
10.1.3.14
Security
Appliance
ftp.cisco.com
10.1.3.14
Static Translation
on Outside to:
209.165.201.10