EPP

What is EPP (Extensible Provisioning Protocol)?

EPP (Extensible Provisioning Protocol) is a standardized XML-based protocol used for communication between domain name registrars and registries. It provides a consistent, secure framework for domain registration, transfer, renewal, and management operations. EPP has become the industry standard, replacing older protocols and enabling interoperability across the domain name system.

How EPP works

Communication model

Registrar ←→ EPP Server ←→ Registry Database
    ↑                              ↓
 Customer                    Domain Records

EPP operations

EPP message structure

Request example

<?xml version="1.0" encoding="UTF-8"?>
<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
  <command>
    <check>
      <domain:check xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
        <domain:name>example.com</domain:name>
      </domain:check>
    </check>
  </command>
</epp>

Response

Contains result codes, domain status, and any error messages.

EPP status codes

Client statuses

• clientHold: Domain suspended by registrar
• clientTransferProhibited: Transfer blocked
• clientUpdateProhibited: Updates blocked
• clientDeleteProhibited: Deletion blocked

Server statuses

• serverHold: Domain suspended by registry
• serverTransferProhibited: Registry-level transfer lock
• pendingCreate: Registration processing
• pendingDelete: Domain being deleted

EPP authorization code

Also called:

• Auth code
• EPP code
• Transfer key

Used for:

• Domain transfers between registrars
• Proving ownership/control
• Security verification

EPP security features

Authentication

• Client certificates
• Username/password
• Session management

Transport security

• TLS encryption required
• Secure TCP connections
• Certificate validation

EPP in domain transfers

Transfer process

1. Current registrar generates EPP auth code

2. Gaining registrar submits transfer request with code

3. Losing registrar receives notification

4. 5-day approval/rejection window

5. Transfer completes or is rejected

Transfer statuses

• pendingTransfer
• clientTransferApproved
• serverTransferApproved
• transferRejected

EPP extensions

Base EPP can be extended for:

• DNSSEC management
• Registry-specific features
• Premium domain handling
• Grace period information

Why EPP matters

For registrars

• Standardized integration
• Consistent API across registries
• Automated domain management
• Secure transactions

For domain owners

• Reliable domain operations
• Consistent experience across registrars
• Secure transfer mechanism
• Status transparency

EPP is the backbone protocol enabling the modern domain name registration system to function reliably and securely across thousands of registrars and registries.