Method for dynamic updating of DNS information in an IP network, comprising the following steps: - a first entity of said IP network, distinct from the DNS servers of the IP network, receives (E1, F1, G1, H1) a request (SIP REGISTER, SIP INVITE) from a second entity of the IP network, it also being distinct from the DNS servers of the IP network but having a copy of information, called DNS information, on a type forming the subject of a registration in at least one DNS server of the IP network, - said first entity responds (E2, F2, G2, H2) to said request (SIP REGISTER, SIP INVITE) by sending to said second entity a message comprising an indication (Flush-DNS) relating to the need to modify said copy, - following the reception of said message sent by the first entity, the second entity scans the message (E3, F3, G3, H3) to determine whether said indication ( Flush-DNS) contains at least one additional instruction ( do-not-check, remove, add, modify, ttl, priority), and - in the event of positive determination, the second entity: • performs a DNS interrogation (E4, F4), and, following the reception (E5, F5) of the response from the interrogated DNS server, modifies (E6, F6) its copy of said DNS information on the basis of the content of said response and of said additional instruction ( remove, add, modify, ttl, priority), or • modifies its copy of said DNS information on the basis of said additional instruction ( remove, add, modify, ttl, priority) without performing a DNS interrogation ( do-not-check). - a first entity of said IP network, distinct from the DNS servers of the IP network, receives (E1, F1, G1, H1) a request (SIP REGISTER, SIP INVITE) from a second entity of the IP network, it also being distinct from the DNS servers of the IP network but having a copy of information, called DNS information, on a type forming the subject of a registration in at least one DNS server of the IP network, - said first entity responds (E2, F2, G2, H2) to said request (SIP REGISTER, SIP INVITE) by sending to said second entity a message comprising an indication (Flush-DNS) relating to the need to modify said copy, - following the reception of said message sent by the first entity, the second entity scans the message (E3, F3, G3, H3) to determine whether said indication ( Flush-DNS) contains at least one additional instruction ( do-not-check, remove, add, modify, ttl, priority), and - in the event of positive determination, the second entity: • performs a DNS interrogation (E4, F4), and, following the reception (E5, F5) of the response from the interrogated DNS server, modifies (E6, F6) its copy of said DNS information on the basis of the content of said response and of said additional instruction ( remove, add, modify, ttl, priority), or • modifies its copy of said DNS information on the basis of said additional instruction ( remove, add, modify, ttl, priority) without performing a DNS interrogation ( do-not-check). • performs a DNS interrogation (E4, F4), and, following the reception (E5, F5) of the response from the interrogated DNS server, modifies (E6, F6) its copy of said DNS information on the basis of the content of said response and of said additional instruction ( remove, add, modify, ttl, priority), or • modifies its copy of said DNS information on the basis of said additional instruction ( remove, add, modify, ttl, priority) without performing a DNS interrogation ( do-not-check).