Ошибка ldap расширения не загружены

This is my Action

public function loginAction()
{
    $request= $this->getRequest();
    if($request->isPost())
    {
        $username= $request->getPost('email');
        $password= $request->getPost('password');

        $auth = new AuthenticationService();
        $adapter = new AuthAdapter(
            array('server1'=>array(
                'host' => '192.168.1.4',
                'useStartTls' => false,
                'useSsl' => false,
                'accountDomainName' => 'coasting',
                'accountDomainNameShort' => 'DOMAIN',
                'accountCanonicalForm' => 3,
                'accountFilterFormat' => '(&(objectClass=user)(sAMAccountName=%s))',
                'baseDn' => 'CN=Users,DC=domain,DC=local',
                'bindRequiresDn' => false,
                'optReferrals' => false
            )), 
            $username, 
            $password
        );
        $result = $auth->authenticate($adapter);

        print_r($result);
    }

}

after running this action following error will showing ‘0x7002: LDAP extension not loaded’,

/var/www/coasting/vendor/zendframework/zendframework/library/Zend/Authentication/Adapter/Ldap.php(140): ZendLdapLdap->__construct()

/var/www/coasting/vendor/zendframework/zendframework/library/Zend/Authentication/Adapter/Ldap.php(205): ZendAuthenticationAdapterLdap->getLdap()

/var/www/coasting/vendor/zendframework/zendframework/library/Zend/Authentication/AuthenticationService.php(110): ZendAuthenticationAdapterLdap->authenticate()

How can i solve this error. If any other settings?

This is my Action

public function loginAction()
{
    $request= $this->getRequest();
    if($request->isPost())
    {
        $username= $request->getPost('email');
        $password= $request->getPost('password');

        $auth = new AuthenticationService();
        $adapter = new AuthAdapter(
            array('server1'=>array(
                'host' => '192.168.1.4',
                'useStartTls' => false,
                'useSsl' => false,
                'accountDomainName' => 'coasting',
                'accountDomainNameShort' => 'DOMAIN',
                'accountCanonicalForm' => 3,
                'accountFilterFormat' => '(&(objectClass=user)(sAMAccountName=%s))',
                'baseDn' => 'CN=Users,DC=domain,DC=local',
                'bindRequiresDn' => false,
                'optReferrals' => false
            )), 
            $username, 
            $password
        );
        $result = $auth->authenticate($adapter);

        print_r($result);
    }

}

after running this action following error will showing ‘0x7002: LDAP extension not loaded’,

/var/www/coasting/vendor/zendframework/zendframework/library/Zend/Authentication/Adapter/Ldap.php(140): ZendLdapLdap->__construct()

/var/www/coasting/vendor/zendframework/zendframework/library/Zend/Authentication/Adapter/Ldap.php(205): ZendAuthenticationAdapterLdap->getLdap()

/var/www/coasting/vendor/zendframework/zendframework/library/Zend/Authentication/AuthenticationService.php(110): ZendAuthenticationAdapterLdap->authenticate()

How can i solve this error. If any other settings?