用下面这段代码，来反查一个百度IP 220.181.108.145 的域名，查询失败：
local resolver = require "resty.dns.resolver"
local r, err = resolver:new{
nameservers = {"114.114.114.114", "223.5.5.5"},
retrans = 5, -- 5 retransmissions on receive timeout
timeout = 2000, -- 2 sec
}
if not r then
ngx.say("failed to instantiate the resolver: ", err)
return
end
local answers, err = r:query("145.108.181.220.in-addr.arpa", TYPE_PTR)
if not answers then
ngx.say("failed to query the DNS server: ", err)
return
end
if answers.errcode then
ngx.say("server returned error code: ", answers.errcode,
": ", answers.errstr)
end
for i, ans in ipairs(answers) do
ngx.say(ans.name, " ", ans.address or ans.cname,
" type:", ans.type, " class:", ans.class,
" ttl:", ans.ttl)
end
这个没有任何输出。
我直接用dig查是可以的：
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请教下，是什么原因呢，非常感激？
