The so-called notice-and-take-down provisions of the Digital Millennium Copyright Act (DMCA) provide both a very effective tool for copyright owners to get infringing content removed from the Internet as well as an important protection for service providers (such as website hosting companies) that may inadvertently publish infringing material, either directly or via user-generated content.

But, the DMCA is neither a perfect weapon or shield. It cannot be invoked in every instance of online infringement—and, even when it does apply, the DMCA is not always productive.

Here are five (of many!) myths and truths about limitations on the DMCA take-down notice process.

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Myth #1: A service provider is required to take down allegedly infringing content if it receives a proper notice under the DMCA.

Truth: The DMCA does not require a service provider to take down allegedly infringing content. Instead, the DMCA gives service providers an incentive to do so by providing that they “shall not be liable for monetary relief” if they comply with a proper DMCA notice. Not all service providers have opted into the DMCA system, and even those who have opted-in are not obligated to take down content.

Myth #2: Service providers are required to take down infringing content within 24 hours of receiving a proper DMCA notice.

Truth: The DMCA does not specify a timeline for a service provider to take down allegedly infringing content. Instead, the DMCA requires only that service providers “act[] expeditiously to remove, or disable access to, the material.” In practice, however, service providers familiar with the DMCA often take down infringing content within 24 hours.

Myth #3: Every U.S.-based service provider is obligated to comply with the DMCA process.

Truth: Service providers (in the United States and elsewhere) must opt-into the DMCA system if they want to avail themselves of its protections—and many fail to do so. The DMCA protections apply “only if the service provider has designated an agent to receive notifications of claimed infringement.” A list of agents is available at the U.S. Copyright Office.

Myth #4: If a service provider has not appointed a DMCA agent at the U.S. Copyright Office, there’s no reason for a copyright owner to send a take-down notice.

Truth: Many service providers that have not opted into the DMCA system nevertheless act in accordance with the DMCA. In other words, a copyright owner may find it worthwhile to submit a DMCA take-down notice to a service provider even if the providerhas not appointed an agent, because the service provider may remove the infringing content upon receipt of the notice.

Myth #5: Once a service provider has taken down infringing content in response to a DMCA notice, the content will be permanently removed.

Truth: An alleged infringer can file a “counter notification” in response to a copyright owner’s take-down notice. If that occurs, the service provider may, under certain circumstances, restore access to the allegedly infringing content and remain exempt from liability.