distributed-dig

distributed-dig

Quick Start

• Install globally using npm install -g distributed-dig
• Run ddig [domain [domain] ...] [options]

Overview

Issues multiple DNS lookup requests across a multitude of DNS resolvers.

Useful for checking if a DNS record has been fully propagated, or for querying the origins behind an AWS Route 53 / Azure Traffic Manager record (or any other DNS-based load balancing solution).

Installation

Installing globally is recommended:

npm install -g distributed-dig

Usage

ddig domain [domain [domain] ...] [options]

Options

The following options are available:

   --port <number>                  Specify the DNS port [53]
   --protocol <upd|tcp>             Specify the DNS protocol [udp]
   --timeout <number>               Specify the DNS timeout in milliseconds [2500]
   --edns <true|false>              Enable or disable EDNS(0) [false]
   --list-resolvers                 List resolvers configured in config file
   --list-options                   List DNS request options configured in config file
   --verbose                        Outputs more information
   --no-color                       Switches off colour output
   --version                        Display version number
   --help                           Display this help

help

Displays the help screen:

port

Specify the TCP/UDP port tro use when connecting to the DNS resolver. Default: 53

protocol

Specify whether to use UDP or TCP when connecting to the DNS resolver. Default: udp

timeout

Specifies the timeout in milliseconds to wait for a response from each DNS resolver. Default: 2500 (2.5 seconds)

edns

Enables EDNS(0) Default: false (disabled)

With EDNS(0) enabled, if an upstream resolver doesn't support it then the standard DNS will be used as a fallback. Even though EDNS is support by ~90% of resolvers on the internet ¹, it is disabled by default in ddig as it may cause the resolver to return the IP address it considers closest to you, which is counterproductive to the purpose of querying many geographically distributed DNS resolvers.

list-resolvers

Lists the resolvers configured in the distributed-dig.json config file:

list-options

Lists the options configured in the distributed-dig.json config file:

verbose

Switches on verbose mode which outputs additional fields:

• Full recursive answer (i.e. nested cname records)
• Resolver IP Address
• Response time

--verbose also modifies the --list-resolvers and --list-options switches.

no-color

If your terminal has problems rendering the colour output then you can switch it off by using --no-color

version

Prints out distributed-dig's version number.

Examples

Lookup a single domain

• List the IP address returned for www.asos.com from each of the configured resolver:

ddig www.asos.com

Lookup a single domain with verbose enabled

• List the IP address and full recursive path returned for www.asos.com from each of the configured resolver:

ddig www.asos.com --verbose

Lookup multiple domains with an increased timeout

• List the IP addresses returned for both www.asos.com & secure.asos.com from each of the configured resolver with a 5 second timeout:

ddig www.asos.com my.asos.com secure.asos.com --timeout 5000

Features

Unique IP Address Identifier

The first occurrence of each unique IP address is marked by a bullet point:

Column Width Warning

If you use the --verbose switch and have a terminal window that's narrower than 130 columns you'll see a warning:

Configuration File

All Options and Resolvers are configured in distributed-dig.json file. This file can exist in any of the following locations:

• The current working directory - node -p process.cwd()
• The home directory - node -p require('os').homedir()
• The application's root directory (i.e. the same directory as distributed-dig.js)

Request Options

The default options are:

"options": {
    "request": {
      "port": 53,
      "type": "udp",
      "timeout": 2500,
      "try_edns": false,
      "cache": false
    },
    "question": {
      "type": "A"
    }
}

DNS Resolvers

Resolvers are configured in an array with each resolver having a nameServer element which should be the IPv4 or IPv6 address, and a provider element which is just a freeform text label:

"resolvers": [
    {
      "nameServer": "208.67.222.222",
      "provider": "OpenDNS (Primary)"
    },
    {
      "nameServer": "208.67.220.220",
      "provider": "OpenDNS (Secondary)"
    },
    {
      "nameServer": "217.199.173.113",
      "provider": "United Kingdom"
    }
]

You can find a list of public DNS servers here and tailor the configured list for your own requirements.

Debugging

distributed-dig uses the npm package debug. If you set the environment variable debug to ddig you'll see full debug output.

Windows

set debug=ddig

Linux

DEBUG=ddig

Powershell

$env:debug="ddig"

FAQ

Question: What terminal/console are you using in the screen shots?

Answer: A pre-release of Microsoft's new tabbed Windows Terminal which has many excellent features, and the ability to configure a background image.

Footnotes

1. Internet Systems Consortium - Partial EDNS Compliance Hampers Deployment of New DNS Features ↩