ZyXEL Communications P-334WT Support Notes page 19

Without DDNS, we always tell the users to use the WAN IP of the Prestige to reach our internal server.
It is inconvenient for the users if this IP is dynamic. With DDNS supported by the Prestige, you apply a
DNS name (e.g., www.zyxel.com.tw) for your server (e.g., Web server) from a DDNS server. The
outside users can always access the web server using the www.zyxel.com.tw regardless of the WAN IP
of the Prestige.
When the ISP assigns the Prestige a new IP, the Prestige updates this IP to DDNS server so that the
server can update its IP-to-DNS entry. Once the IP-to-DNS table in the DDNS server is updated, the
DNS name for your web server (i.e., www.zyxel.com.tw) is still usable.
13. When do I need DDNS service?
When you want your internal server to be accessed by using DNS name rather than using the dynamic IP
address we can use the DDNS service. The DDNS server allows to alias a dynamic IP address to a static
hostname. Whenever the ISP assigns you a new IP, the Prestige sends this IP to the DDNS server for its
updates.
14. What DDNS servers does the Prestige support?
The DDNS servers the Prestige supports currently is WWW.DYNDNS.ORG where you apply the DNS
from and update the WAN IP to.
15. What is DDNS wildcard?
Some DDNS servers support the wildcard feature which allows the hostname, *.yourhost.dyndns.org, to
be aliased to the same IP address as yourhost.dyndns.org. This feature is useful when there are multiple
servers inside and you want users to be able to use things such as www.yourhost.dyndns.org and still
reach your hostname.
16. Does the Prestige support DDNS wildcard?
Yes, the Prestige supports DDNS wildcard that WWW.DynDNS.ORG supports. When using wildcard,
you simply enter yourhost.dyndns.org in the Host field in Menu 1.1.
17. Can the Prestige SUA handle IPsec packets sent by the IPsec gateway?
Yes, the Prestige's SUA can handle IPsec ESP Tunneling mode. We know when packets go through
SUA, SUA will change the source IP address and source port for the host. To pass IPsec packets, SUA
must understand the ESP packet with protocol number 50, replace the source IP address of the IPsec
gateway to the router's WAN IP address. However, SUA should not change the source port of the UDP