A method for obtaining a local domain name, comprising: receiving, by a second server, from a third server an access success message containing a domain name of a local domain where a User Equipment, UE, is located after the UE performing EAP access full authentication with the third server succeeds, and saving, by the second server, the domain name of the local domain where the UE is located; wherein the domain name of the local domain is a domain name of a domain where a current network to which the UE is attached is located and wherein the current network is a visited network; receiving, by the second server, a Dynamic Host Configuration Protocol, DHCP, request of the UE to a first server, wherein the DHCP request carries an option for indicating returning the domain name of the local domain where the UE is located; inserting, by the second server, the domain name of the local domain where the UE is located into the DHCP request, and forwarding the DHCP request to the first server; receiving, by the second server, a DHCP reply message returned by the first server, and forwarding the DHCP reply message to the UE, wherein the DHCP reply message carries the domain name of the local domain where the UE is located, wherein the domain name of the local domain is for use in re-authentication of the UE during a handover; wherein the first server is a DHCP server, the second server is a DHCP relay or a DHCP agent; and the third server is an Extensible Authentication Protocol, EAP, server, an Authentication, Authorization and Accounting, AAA, server with an EAP Re-authentication Protocol, ERP, function, or an AAA server with an EAP function. receiving, by a second server, from a third server an access success message containing a domain name of a local domain where a User Equipment, UE, is located after the UE performing EAP access full authentication with the third server succeeds, and saving, by the second server, the domain name of the local domain where the UE is located; wherein the domain name of the local domain is a domain name of a domain where a current network to which the UE is attached is located and wherein the current network is a visited network; receiving, by the second server, a Dynamic Host Configuration Protocol, DHCP, request of the UE to a first server, wherein the DHCP request carries an option for indicating returning the domain name of the local domain where the UE is located; inserting, by the second server, the domain name of the local domain where the UE is located into the DHCP request, and forwarding the DHCP request to the first server; receiving, by the second server, a DHCP reply message returned by the first server, and forwarding the DHCP reply message to the UE, wherein the DHCP reply message carries the domain name of the local domain where the UE is located, wherein the domain name of the local domain is for use in re-authentication of the UE during a handover; wherein the first server is a DHCP server, the second server is a DHCP relay or a DHCP agent; and the third server is an Extensible Authentication Protocol, EAP, server, an Authentication, Authorization and Accounting, AAA, server with an EAP Re-authentication Protocol, ERP, function, or an AAA server with an EAP function.