对于KVM虚拟机，可以直接在创建虚拟机的时候勾上NAT，这时候就会自动为虚拟机分配一个虚拟的子网并且虚拟机可以通过nat连接到外部网络，基本上是开箱即用。同时也支持端口映射，具体可参考官方wiki下的QEMU port redirection。但之前在使用的过程中，发现这个端口映射并不是很稳定。同时虽然这种方法很简单，但是虚拟机之间是隔离的，无法互通数据，这样就非常不灵活。
同时，LXC虚拟机是没有这种开箱即用的NAT的。
这里我们可以看到有"The server could not connect to the client to verify the domain"的错误提示信息，包括也有其他提示错误，"The server experienced an internal error :: Error creating new registration"我们在邮局的时候不要用国内免费邮局。所以，如果我们是海外域名就直接先用域名自带的DNS。
// take order for table 1 and wait...
var order1 = orderBlocking(['Coke', 'Iced Tea']);
// once order is ready, take order back to table.
serveOrder(order1);
// once order is delivered, move on to another table.
// take order for table 2 and wait...
var order2 = orderBlocking(['Coke', 'Water']);
// once order is ready, take order back to table.
serveOrder(order2);
// once order is delivered, move on to another table.
// take order for table 3 and wait...
var order3 = orderBlocking(['Iced Tea', 'Water']);
// once order is ready, take order back to table.
serveOrder(order3);
// once order is delivered, move on to another table.
// take order for table 1 and move on...
orderNonBlocking(['Coke', 'Iced Tea'], function(drinks){
return serveOrder(drinks);
});
// take order for table 2 and move on...
orderNonBlocking(['Beer', 'Whiskey'], function(drinks){
return serveOrder(drinks);
});
// take order for table 3 and move on...
orderNonBlocking(['Hamburger', 'Pizza'], function(food){
return serveOrder(food);
});
if (typeof Object.create !== 'function') {
Object.create = function (o) {
var F = function {};
F.prototype = o;
return new F;
};
var otherPerson = Object.create(person);
// extract a core module like this
var http = require('http);
// extract a user defined module like this
var something = require('./folder1/folder2/folder3/something.js');
4.调整nginx、php-fpm和内核的backlog（积压），connect() to unix:/tmp/php-fpm.socket failed (11: Resource temporarily unavailable) while connecting to upstream错误的返回会减少
