STUN reports a DNS IP Address as the Internal IP

I have an asterisk-1.6.1.0 PBX system connected to the Internet behind a NAT/Firewall router. As such, it is configured to use the stunaddr option. When I issued sip show settings on asterisk CLI, I noticed STUN returned the DNS IP Address (208.69.32.132) as the Internal IP as shown below. How can I fix this problem?

[code]Network Settings:

SIP address remapping: Enabled using STUN
Externhost: my_asterisk.homelinux.net
Externip: w.x.y.z:5060
Externrefresh: 400
Internal IP: 208.69.32.132:5060
Localnet: 192.168.1.0/255.255.255.0
STUN server: 69.0.208.27:3478[/code]