ZyXEL Communications ZyWALL5UTM 4.0 User Manual

ZyWALL 5/35/70 Series User’s Guide

421 

Chapter 26 DNS

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

Figure 203   DNS Cache

The following table describes the labels in this screen.

Table 150   DNS Cache

DNS Cache Setup

Cache Positive DNS 

Resolutions

Select the check box to record the positive DNS resolutions in the cache. 

Caching positive DNS resolutions helps speed up the ZyWALL’s processing of 

commonly queried domain names and reduces the amount of traffic that the 

ZyWALL sends out to the WAN.

Maximum TTL

Type the maximum time to live (TTL) (60 to 3600 seconds). This sets how long 

the ZyWALL is to allow a positive resolution entry to remain in the DNS cache 

before discarding it.

Cache Negative 

DNS Resolutions

Caching negative DNS resolutions helps speed up the ZyWALL’s processing of 

commonly queried domain names (for which DNS resolution has failed) and 

reduces the amount of traffic that the ZyWALL sends out to the WAN.

Negative Cache 

Period

Type the time (60 to 3600 seconds) that the ZyWALL is to allow a negative 

resolution entry to remain in the DNS cache before discarding it.

Apply

Click Apply to save your changes back to the ZyWALL.

Reset

Click Reset to begin configuring this screen afresh.