# DNS Service

Domain Name System (DNS) is a database system for translating domain names to IP addresses, such as www.juniper.net = 207.17.137.68.

To modify one or more of the following settings for DNS, enter a new value in the Current column for the parameter you want to adjust, and then click Apply:

Maximum Cache Size: The maximum size, in bytes, of the DNS cache on the security device. Minimum: 0; maximum: 1,000,000; default: 100.

Maximum Cache Timeout: The maximum number of seconds that the security device stores a query in its cache. Minimum: 0; maximum: 3600; default: 60.

Report Unknowns: Enables or disables the reporting of any unknown DNS TYPE and CLASS parameter. A value of 0 disables such reporting, and 1 enables it. An unknown DNS TYPE or CLASS is anything not defined in one of the following DNS-related RFCs: 1035, 1183, 2535, 1712, 1876, 1886, 1995, 2053, 2065, 2538, 2671, 2672, and 2930. By default, the reporting of unknown DNS parameters is disabled.

Report Unexpected: Enables or disables the reporting of unexpected DNS parameters. A value of 0 disables such reporting, and 1 enables it. By default, the reporting of unexpected DNS parameters is disabled.

Maximum UDP Message Length: Specifies the maximum number of bytes in a UDP message sent during a DNS exchange. Minimum: 512; maximum: 4096; default: 512.

Maximum Size of a NXT Resource Record: The maximum number of bytes in a nonexistent resource record (NXT RR) in a DNS response message. Minimum: 1024; maximum: 8192; default: 4096.