DNS Client and Cache
|Document revision:||1.2 (Fri Apr 15 17:37:43 GMT 2005)|
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.
SpecificationsPackages required: system
License required: Level1
Submenu level: /ip dns
Standards and Technologies: DNS
Hardware usage: Not significant
The MikroTik router with DNS cache feature enabled can be set as a primary DNS server for any DNS-compliant clients. Moreover, MikroTik router can be specified as a primary DNS server under its dhcp-server settings. When the DNS cache is enabled, the MikroTik router responds to DNS TCP and UDP requests on port 53.
Client Configuration and Cache SetupSubmenu level: /ip dns
DNS client is used to provide domain name resolution for router itself as well as for the P2P clients connected to the router.
Property Descriptionallow-remote-requests (yes | no) - specifies whether to allow network requestscache-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 KiBcache-used (read-only: integer) - displays the currently used cache size in KiBprimary-dns (IP address; default: 0.0.0.0) - primary DNS serversecondary-dns (IP address; default: 0.0.0.0) - secondary DNS server
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.
To set 126.96.36.199 as the primary DNS server and allow the router to be used as a DNS server, do the following:
[admin@MikroTik] ip dns> set primary-dns=188.8.131.52 \ \... allow-remote-requests=yes [admin@MikroTik] ip dns> print primary-dns: 184.108.40.206 secondary-dns: 0.0.0.0 allow-remote-requests: yes cache-size: 2048KiB cache-max-ttl: 1w cache-used: 17KiB [admin@MikroTik] ip dns>
Cache MonitoringSubmenu level: /ip dns cache
Property Descriptionaddress (read-only: IP address) - IP address of the hostname (read-only: name) - DNS name of the host ttl (read-only: time) - remaining time-to-live for the record
Static DNS EntriesSubmenu level: /ip dns static
The MikroTik RouterOS has an embedded DNS server feature in DNS cache. It allows you to link the particular domain names with the respective IP addresses and advertize these links to the DNS clients using the router as their DNS server.
Property Descriptionaddress (IP address) - IP address to resolve domain name withname (text) - DNS name to be resolved to a given IP address ttl (time) - time-to-live of the DNS record
To add a static DNS entry for www.example.com to be resolved to 10.0.0.1 IP address:
[admin@MikroTik] ip dns static> add name www.example.com address=10.0.0.1 [admin@MikroTik] ip dns static> print # NAME ADDRESS TTL 0 aaa.aaa.a 220.127.116.11 1d 1 www.example.com 10.0.0.1 1d [admin@MikroTik] ip dns static>
Flushing DNS cacheCommand name: /ip dns cache flush
Command Descriptionflush - clears internal DNS cache
[admin@MikroTik] ip dns> cache flush [admin@MikroTik] ip dns> print primary-dns: 18.104.22.168 secondary-dns: 0.0.0.0 allow-remote-requests: yes cache-size: 2048 KiB cache-max-ttl: 1w cache-used: 10 KiB [admin@MikroTik] ip dns>