The document discusses transitioning to IPv6 for DNS, mail, and web services in the Portuguese public administration. It provides requirements and implementation steps for each service, as well as common issues to watch out for. For DNS, requirements include supporting AAAA records and IPv6 sockets. Implementation involves registering and querying AAAA records and configuring DNS servers for IPv6. Common issues are firewalls blocking IPv6 traffic and resolvers not supporting AAAA queries. For mail, MTAs and MDAs must support IPv6 sockets and DNS must support AAAA/PTR lookups. Implementation involves configuring MTAs and mail servers for IPv6. Common mail issues are firewalls and rate limiting policies not handling IPv6 properly. Web servers require