ZyXEL Communications 2 Plus 20.7 DNS Cache, 20.8 Configure DNS Cache

Chapter 20 DNS

20.7 DNS Cache

DNS cache is the temporary storage area where a router stores responses from DNS servers. When the ZyWALL receives a positive or negative response for a DNS query, it records the response in the DNS cache. A positive response means that the ZyWALL received the IP address for a domain name that it checked with a DNS server within the five second DNS timeout period. A negative response means that the ZyWALL did not receive a response for a query it sent to a DNS server within the five second DNS timeout period.

When the ZyWALL receives DNS queries, it compares them against the DNS cache before querying a DNS server. If the DNS query matches a positive entry, the ZyWALL responses with the IP address from the entry. If the DNS query matches a negative entry, the ZyWALL replies that the DNS query failed.

20.8 Configure DNS Cache

To configure your ZyWALL’s DNS caching, click ADVANCED > DNS > Cache. The screen appears as shown.

Figure 239 ADVANCED > DNS > Cache

	371
ZyWALL 2 Plus User’s Guide