Allied Telesis AT-WR4500 manual DNS Client and Cache, IP and Routing

AT-WR4500 Series - IEEE 802.11abgh Outdoor Wireless Routers	129
RouterOS v3 Configuration and User Guide

6.2DNS Client and Cache

6.2.1General Information

Summary

DNS cache is used to minimize DNS requests to an external DNS server as well as to minimize DNS resolution time. This is a simple recursive DNS server with local items.

Specifications

Packages required: system

License required: Level1

Submenu level: /ip dns

Standards and Technologies: DNS

Hardware usage: Not significant

RelatedTopics

IP and Routing

Description

The RouterOS router with DNS cache feature enabled can be set as a primary DNS server for any DNS- compliant clients. Moreover, RouterOS router can be specified as a primary DNS server under its dhcp- server settings. When the DNS cache is enabled, the RouterOS router responds to DNS TCP and UDP requests on port 53.

Additional Resources

http://www.ietf.org/rfc/rfc1035.txt?number=1035

http://www.freesoft.org/CIE/Course/Section2/3.htm

http://www.networksorcery.com/enp/protocol/dns.htm

http://en.wikipedia.org/wiki/Domain_Name_System

6.3 DNS Cache Setup

Submenu level: /ip dns

Description

DNS facility is used to provide domain name resolution for router itself as well as for the clients connected to it..

Property Description

allow-remote-requests (yes no) - specifies whether to allow network requests cache-max-ttl (time; default: 1w) - specifies maximum time-to-live for cahce records. In other words, cache records will expire after cache-max-ttl time.

cache-size (integer: 512..10240; default: 2048KiB) - specifies the size of DNS cache in KiB

cache-used (read-only: integer) - displays the currently used cache size in KiB

primary-dns (IP address; default: 0.0.0.0) - primary DNS server

secondary-dns (IP address; default: 0.0.0.0) - secondary DNS server

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If the property use-peer-dns under /ip dhcp-client is set to yes then primary-dns under /ip dns will change to a DNS address given by DHCP Server.