Cache
If you perform a query on an A or AAAA type and it doesn't exist, the cache will attempt to lookup a CNAME and then resolve that.
The constructor takes an optional object with the following properties:
store-- implements the cache store model (optional, default MemoryStore)
Methods:
lookup(question, cb)-- for a given question check the cache store for existencestore(packet)-- iterates over the resource records in a packet and sends them to the cache storepurge()-- clears the cache store of all entries
MemoryStore / Cache store model
MemoryStore(opts) -- An in memory store based on a js object
Methods:
get(domain, key, cb)
domainis the holder under which keys will be applied,keyis the subdomain that is being queried for. If youget('example.com', 'www', cb)you are really asking forwww.example.com.cb(err, results)-- results is an object of types and array of answers
{ 1: [{address: '127.0.0.1', ttl: 300, type: 1, class: 1}] }set(domain, key, data, cb)
domainis the parent under which this key is stored.keyis the subdomain we are storing,datais an object of types with an array of answers.
set('example.com', 'www', {1: [{class:1, type:1, ttl:300, address:'127.0.0.1'}]}, cb)
cb(err, data)-- cb merely returns the data that was passed.
delete(domain[, key[, type]], cb)-- delete all from a domain, a domain and key, or a domain a key and a type.
Lookup
Is a mechanism that given a store performs the common resolution pattern.
Given example.com previous added to a store:
www.example.com CNAME foo.bar.example.com.*.example.com A 127.0.0.1
A Lookup(store, 'example.com', {name:'www.example.com', type:1}, cb)
will resolve www to the CNAME and then search for foo.bar.example.com which
will return no results, and then search for *.bar.example.com which will also
return no results, and ultimately searches for *.example.com which will return
the desired record.
Callback will be called with (err, results) where results is an array suitable
for use in Packet.answer