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- DNS caching
- ===========
- User experience may be greatly improved when dns is accelerated. Also, it
- seems like a good idea to keep the number of packages being exchanged
- between node and gateway as small as possible. In order to do this, a
- DNS cache may be used on a node. The dnsmasq instance listening on port
- 53 on the node will be reconfigured to answer requests, use a list of
- upstream servers and a specific cache size if the options listed below are
- added to site.conf. Upstream servers are the DNS servers which are normally
- used by the nodes to resolve hostnames (e.g. gateways/supernodes).
- There are the following settings:
- servers
- cacheentries
- To use the node's DNS server, both options should be set. The node will cache at
- most 'cacheentries' many DNS records in RAM. The 'servers' list will be used to
- resolve the received DNS queries if the request cannot be answered from
- cache. Gateways should announce the "next node" address via DHCP and RDNSS (if
- any). Note that not setting 'servers' here will lead to DNS not working: Once
- the gateways all announce the "next node" address for DNS, there is no way for
- nodes to automatically determine DNS servers. They have to be baked into the
- firmware.
- If these settings do not exist, the cache is not initialized and RAM usage will
- not increase.
- When next_node.name is set, an A record and an AAAA record for the
- next-node IP address are placed in the dnsmasq configuration. This means that the content
- of next_node.name may be resolved even without upstream connectivity. It is suggested to use
- the same name as the DNS server provides: e.g nextnode.yourdomain.net (This way the name also
- works if client uses static DNS Servers). Hint: If next_node.name does not contain a dot some
- browsers would open the searchpage instead.
- ::
- dns = {
- cacheentries = 5000,
- servers = { '2001:db8::1', },
- },
- next_node = {
- name = 'nextnode.yourdomain.net',
- ip6 = '2001:db8:8::1',
- ip4 = '198.51.100.1',
- }
- The cache will be initialized during startup.
- Each cache entry will occupy about 90 bytes of RAM.
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