Nginx Problematic Setup

I want to have a subdomain setup on Nginx. And I have the following configuration following the example from https://wiki.nginx.org/Wordpress. I’m using fastCGI as well

map $http_host $blogid {
	default		-999;
}

server {
	root		/var/www/wordpress;
	index		index.php;
	listen		127.0.0.1:80;
	server_name	idu.host *.idu.host;
	charset		utf-8;

	location / {
		index		index.php;
		try_files	$uri $uri/ /index.php?$args;
	}

	location ~ /\.ht {
		deny		all;
	}

	location ~* \.(js|css|png|jpg|gif|swf|ico|pdf|mov|fla|zip|rar)$ {
		try_files	$uri = 404;
		expires		max;
		log_not_found	off;
	}

	location ~ ^/files/(.*)$ {
		try_files /wp-content/blogs.dir/$blogid/$uri /wp-includes/ms-files.php?file=$1;
		access_log	off;
		expires		max;
		log_not_found	off;
	}

	location ^~ /blogs.dir {
		internal;
		alias /var/www/wordpress/wp-content/blogs.dir;
		access_log	off;
		expires		max;
		log_not_found	off;
	}

	location ~ \.php$ {
		include		/etc/nginx/fastcgi_params;
		fastcgi_pass	127.0.0.1:9000;
		fastcgi_index	index.php;
		fastcgi_pass	php;
		fastcgi_intercept_errors	on;
	}
}

But when I go to idu.host, the DNS lookup didn’t occur.