code: func NewDefaultConfig() *Config {
  	return &Config{
  		IdentityEndpoint:   env.GetOrDefaultString("OTC_IDENTITY_ENDPOINT", defaultIdentityEndpoint),
  		PropagationTimeout: env.GetOrDefaultSecond("OTC_PROPAGATION_TIMEOUT", dns01.DefaultPropagationTimeout),
  		PollingInterval:    env.GetOrDefaultSecond("OTC_POLLING_INTERVAL", dns01.DefaultPollingInterval),
  		TTL:                env.GetOrDefaultInt("OTC_TTL", minTTL),
  		HTTPClient: &http.Client{
  			Timeout: env.GetOrDefaultSecond("OTC_HTTP_TIMEOUT", 10*time.Second),
  			Transport: &http.Transport{
  				Proxy: http.ProxyFromEnvironment,
  				DialContext: (&net.Dialer{
  					Timeout:   30 * time.Second,
  					KeepAlive: 30 * time.Second,
  					DualStack: true,
  				}).DialContext,
  				MaxIdleConns:          100,
  				IdleConnTimeout:       90 * time.Second,
  				TLSHandshakeTimeout:   10 * time.Second,
  				ExpectContinueTimeout: 1 * time.Second,
  
  				// Workaround for keep alive bug in otc api
  				DisableKeepAlives: true,
  			},
  		},
  	}
  }
docs: // NewDefaultConfig returns a default configuration for the DNSProvider