diff --git a/README.md b/README.md
index 7e631d3..b0224f1 100644
--- a/README.md
+++ b/README.md
@@ -72,21 +72,23 @@ $order = $client->createOrder(['example.org', 'www.example.org']);
 In the example above the primary domain is followed by a secondary domain(s). Make sure that for each domain you are 
 able to prove ownership. As a result the certificate will be valid for all provided domains.
 
+
 ### Prove ownership
 
-Before you can obtain a certificate for a given domain you need to prove that you own the given domain(s). In this 
-example we will show you how to do this for http-01 validation (where serve specific content at a specific url on the
-domain, like: `example.org/.well-known/acme-challenge/*`).
-
-Obtain the authorizations for order. For each domain supplied in the create order request an authorization is returned.
-
+Before you can obtain a certificate for a given domain you need to prove that you own the given domain(s).
+We request the authorizations to prove ownership. Obtain the authorizations for order. For each domain supplied in the 
+create order request an authorization is returned.                                     
 ```php
 $authorizations = $client->authorize($order);
 ```
-
-
 You now have an array of `Authorization` objects. These have the challenges you can use (both `DNS` and `HTTP`) to 
-provide proof of ownership.
+provide proof of ownership. 
+
+
+#### HTTP validation
+
+HTTP validation (where serve specific content at a specific url on the domain, like: 
+`example.org/.well-known/acme-challenge/*`) is done as follows:
 
 Use the following example to get the HTTP validation going. First obtain the challenges, the next step is to make the 
 challenges accessible from 
@@ -97,26 +99,62 @@ foreach ($authorizations as $authorization) {
 }
 ```
 
-Now that the challenges are in place and accessible through `example.org/.well-known/acme-challenge/*` we can request 
-validation. 
+
+#### DNS validation
+You can also use DNS validation - to do this, you will need access to an API of your DNS 
+provider to create TXT records for the target domains.
+
+```php
+foreach ($authorizations as $authorization) {
+    $txtRecord = $authorization->getTxtRecord();
+    
+    //To get the name of the TXT record call:
+    $txtRecord->getName();
+
+    //To get the value of the TXT record call:
+    $txtRecord->getValue();
+}
+```
+
+
+### Self test
+
+After exposing the challenges (made accessible through HTTP or DNS) we can perform a self test just to 
+be sure it works. For a DNS test call:
+
+```php
+$client->selfTest($authorization, Client::VALIDATON_DNS);
+``` 
+
+For a HTTP challenge test call:
+```php
+$client->selfTest($authorization, Client::VALIDATION_HTTP);
+```
+
 
 ### Request validation
 
 Next step is to request validation of ownership. For each authorization (domain) we ask LetsEncrypt to verify the 
 challenge. 
 
+For HTTP validation:
 ```php
 foreach ($authorizations as $authorization) {
-    if ($client->selfTest($authorization, Client::VALIDATION_HTTP)) {
-        $client->validate($authorization->getHttpChallenge(), 15);
-    }
-   
+    $client->validate($authorization->getHttpChallenge(), 15);
+}
+```
+
+For DNS validation:
+```php
+foreach ($authorizations as $authorization) {
+    $client->validate($authorization->getDnsChallenge(), 15);
 }
 ```
 
 The code above will first perform a self test and, if successful, will do 15 attempts to ask LetsEncrypt to validate the challenge (with 1 second intervals) and
 retrieve an updated status (it might take Lets Encrypt a few seconds to validate the challenge).
 
+
 ### Get the certificate
 
 Now to know if we can request a certificate for the order, test if the order is ready as follows:
diff --git a/src/Client.php b/src/Client.php
index 27d1996..378c5e7 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -55,6 +55,11 @@ class Client
      */
     const VALIDATION_HTTP = 'http-01';
 
+    /**
+     * DNS validation
+     */
+    const VALIDATION_DNS = 'dns-01';
+
     /**
      * @var string
      */
@@ -262,6 +267,8 @@ class Client
     {
         if ($type == self::VALIDATION_HTTP) {
             return $this->selfHttpTest($authorization, $maxAttempts);
+        } elseif ($type == self::VALIDATION_DNS) {
+            return $this->selfDNSTest($authorization, $maxAttempts);
         }
     }
 
@@ -289,7 +296,9 @@ class Client
                 $this->signPayloadKid(null, $challenge->getAuthorizationURL())
             );
             $data = json_decode((string)$response->getBody(), true);
-            sleep(ceil(15 / $maxAttempts));
+            if ($maxAttempts > 1) {
+                sleep(ceil(15 / $maxAttempts));
+            }
             $maxAttempts--;
         } while ($maxAttempts > 0 && $data['status'] != 'valid');
 
@@ -389,21 +398,17 @@ class Client
      */
     protected function selfHttpTest(Authorization $authorization, $maxAttempts)
     {
-        $file = $authorization->getFile();
-        $authorization->getDomain();
         do {
             $maxAttempts--;
-
             try {
                 $response = $this->getSelfTestClient()->request(
                     'GET',
-                    'http://' . $authorization->getDomain() . '/.well-known/acme-challenge/' . $file->getFilename()
+                    'http://' . $authorization->getDomain() . '/.well-known/acme-challenge/' .
+                    $authorization->getFile()->getFilename()
                 );
                 $contents = (string)$response->getBody();
-                if ($contents == $file->getContents()) {
-                    {
-                        return true;
-                    }
+                if ($contents == $authorization->getFile()->getContents()) {
+                    return true;
                 }
             } catch (RequestException $e) {
             }
@@ -412,6 +417,56 @@ class Client
         return false;
     }
 
+    /**
+     * Self DNS test client that uses Cloudflare's DNS API
+     * @param Authorization $authorization
+     * @param $maxAttempts
+     * @return bool
+     */
+    protected function selfDNSTest(Authorization $authorization, $maxAttempts)
+    {
+        do {
+            $response = $this->getSelfTestDNSClient()->get(
+                '/dns-query',
+                [
+                    'query' => [
+                        'name' => $authorization->getTxtRecord()->getName(),
+                        'type' => 'TXT'
+                    ]
+                ]
+            );
+            $data = json_decode((string)$response->getBody(), true);
+            if (isset($data['Answer'])) {
+                foreach ($data['Answer'] as $result) {
+                    if (trim($result['data'], "\"") == $authorization->getTxtRecord()->getValue()) {
+                        return true;
+                    }
+                }
+            }
+            if ($maxAttempts > 1) {
+                sleep(ceil(45 / $maxAttempts));
+            }
+            $maxAttempts--;
+        } while ($maxAttempts > 0);
+
+        return false;
+    }
+
+    /**
+     * Return the preconfigured client to call Cloudflare's DNS API
+     * @return HttpClient
+     */
+    protected function getSelfTestDNSClient()
+    {
+        return new HttpClient([
+            'base_uri' => 'https://cloudflare-dns.com',
+            'connect_timeout' => 10,
+            'headers' => [
+                'Accept' => 'application/dns-json',
+            ],
+        ]);
+    }
+
     /**
      * Initialize the client
      */
diff --git a/src/Data/Authorization.php b/src/Data/Authorization.php
index 7760a1c..44acfe6 100644
--- a/src/Data/Authorization.php
+++ b/src/Data/Authorization.php
@@ -3,6 +3,7 @@
 namespace Afosto\Acme\Data;
 
 use Afosto\Acme\Client;
+use Afosto\Acme\Helper;
 
 class Authorization
 {
@@ -93,6 +94,20 @@ class Authorization
         return false;
     }
 
+    /**
+     * @return Challenge|bool
+     */
+    public function getDnsChallenge()
+    {
+        foreach ($this->getChallenges() as $challenge) {
+            if ($challenge->getType() == Client::VALIDATION_DNS) {
+                return $challenge;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Return File object for the given challenge
      * @return File|bool
@@ -105,4 +120,22 @@ class Authorization
         }
         return false;
     }
+
+    /**
+     * Returns the DNS record object
+     *
+     * @param Challenge $challenge
+     * @return Record|bool
+     */
+    public function getTxtRecord()
+    {
+        $challenge = $this->getDnsChallenge();
+        if ($challenge !== false) {
+            $hash = hash('sha256', $challenge->getToken() . '.' . $this->digest, true);
+            $value = Helper::toSafeString($hash);
+            return new Record('_acme-challenge.' . $this->getDomain(), $value);
+        }
+
+        return false;
+    }
 }
diff --git a/src/Data/Record.php b/src/Data/Record.php
new file mode 100644
index 0000000..f1a9fa2
--- /dev/null
+++ b/src/Data/Record.php
@@ -0,0 +1,46 @@
+<?php
+
+namespace Afosto\Acme\Data;
+
+class Record
+{
+
+    /**
+     * @var string
+     */
+    protected $name;
+
+    /**
+     * @var string
+     */
+    protected $value;
+
+    /**
+     * Record constructor.
+     * @param string $name
+     * @param string $value
+     */
+    public function __construct(string $name, string $value)
+    {
+        $this->name = $name;
+        $this->value = $value;
+    }
+
+    /**
+     * Return the DNS TXT record name for validation
+     * @return string
+     */
+    public function getName(): string
+    {
+        return $this->name;
+    }
+
+    /**
+     * Return the record value for DNS validation
+     * @return string
+     */
+    public function getValue(): string
+    {
+        return $this->value;
+    }
+}
diff --git a/src/Helper.php b/src/Helper.php
index 70b5ed8..da5ae14 100644
--- a/src/Helper.php
+++ b/src/Helper.php
@@ -92,11 +92,11 @@ class Helper
         file_put_contents($fn, implode("\n", $config));
         $csr = openssl_csr_new([
             'countryName' => 'NL',
-            'commonName'  => $primaryDomain,
+            'commonName' => $primaryDomain,
         ], $key, [
-            'config'         => $fn,
+            'config' => $fn,
             'req_extensions' => 'SAN',
-            'digest_alg'     => 'sha512',
+            'digest_alg' => 'sha512',
         ]);
         unlink($fn);