I am getting `getAddrInfo ENOTFOUND localhost` on running simple node server even though localhost is present in /etc/hosts (MacOS El Capitan)

Question

I have a very weird thing happening while setting up and running a normal node js server.

When I run node server.js, I get following error:

Server running at http://localhost:1337/
events.js:160
  throw er; // Unhandled 'error' event
  ^
Error: getaddrinfo ENOTFOUND localhost
       at errnoException (dns.js:28:10)
       at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:76:26)

When I open http://localhost:1337/ in my browser, it says page does not exist.

When I run sudo node server.js, it runs fine without any error and I can access my site at https://localhost:1337

Here is my /etc/hosts file:

127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
fe80::1%lo0 localhost

My server.js:

// Require what we need
var http = require("http");
// Build the server
var app = http.createServer(function(request, response {
    response.writeHead(200, {
        "Content-Type": "text/plain"
    });
response.end("Hello world!\n");
});
// Start that server, baby
app.listen(1337, "localhost");
console.log("Server running at http://localhost:1337/");

Other Details

1. OS: Mac OS (El Capitan)
2. Node JS version: 6.10.3 (installed globally)
3. NPM version: 4.5.0 (installed globally)

Following are my questions

1. Why is the above server.js file working with admin access but not as a normal user?
2. Does globally installed node only work with admin access?
3. Is there anything else in Mac OS which can affect DNS lookup other than /etc/hosts? I have already flushed my DNS cache and reboot my OS just to make sure that older DNS lookup is not being used.

Answer 1

I have fixed this same error by editing the file /etc/hosts

Added the lines:

##
##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost