An access method using a domain name system, comprising: receiving, by a network access apparatus, a domain name system, DNS, query request packet sent by user equipment, UE, wherein the DNS query request packet comprises a target domain name, and the DNS query request packet is used to request an Internet Protocol, IP, address that is of a network application server and that corresponds to the target domain name; querying, by the network access apparatus, a locally cached correspondence between a domain name and an IP address according to the target domain name; generating, by the network access apparatus, a first DNS response packet if the target domain name is recorded in the correspondence, wherein the first DNS response packet comprises the target domain name and a first IP address, and the first IP address is an IP address that corresponds to the target domain name and that is recorded in the locally cached correspondence between a domain name and an IP address; and sending, by the network access apparatus, the first DNS response packet to the UE, characterized by if the target domain name is recorded in the correspondence between a domain name and an IP address according to the target domain name: sending, by the network access apparatus, the DNS query request packet to a DNS server, so that the DNS server queries, according to the target domain name, a correspondence that is stored in the DNS server and that is between a domain name and an IP address, and determines an IP address corresponding to the target domain name, and the DNS server generates a second DNS response packet according to the target domain name and the IP address corresponding to the target domain name, and sends the second DNS response packet to the network access apparatus; receiving, by the network access apparatus, the second DNS response packet sent by the DNS server, wherein the second DNS response packet comprises the target domain name and a second IP address, and the second IP address is an IP address that corresponds to the target domain name and that is recorded in the correspondence that is stored in the DNS server and that is between a domain name and an IP address; and sending, by the network access apparatus, the second DNS response packet to the UE. receiving, by a network access apparatus, a domain name system, DNS, query request packet sent by user equipment, UE, wherein the DNS query request packet comprises a target domain name, and the DNS query request packet is used to request an Internet Protocol, IP, address that is of a network application server and that corresponds to the target domain name; querying, by the network access apparatus, a locally cached correspondence between a domain name and an IP address according to the target domain name; generating, by the network access apparatus, a first DNS response packet if the target domain name is recorded in the correspondence, wherein the first DNS response packet comprises the target domain name and a first IP address, and the first IP address is an IP address that corresponds to the target domain name and that is recorded in the locally cached correspondence between a domain name and an IP address; and sending, by the network access apparatus, the first DNS response packet to the UE, characterized by if the target domain name is recorded in the correspondence between a domain name and an IP address according to the target domain name: sending, by the network access apparatus, the DNS query request packet to a DNS server, so that the DNS server queries, according to the target domain name, a correspondence that is stored in the DNS server and that is between a domain name and an IP address, and determines an IP address corresponding to the target domain name, and the DNS server generates a second DNS response packet according to the target domain name and the IP address corresponding to the target domain name, and sends the second DNS response packet to the network access apparatus; receiving, by the network access apparatus, the second DNS response packet sent by the DNS server, wherein the second DNS response packet comprises the target domain name and a second IP address, and the second IP address is an IP address that corresponds to the target domain name and that is recorded in the correspondence that is stored in the DNS server and that is between a domain name and an IP address; and sending, by the network access apparatus, the second DNS response packet to the UE. sending, by the network access apparatus, the DNS query request packet to a DNS server, so that the DNS server queries, according to the target domain name, a correspondence that is stored in the DNS server and that is between a domain name and an IP address, and determines an IP address corresponding to the target domain name, and the DNS server generates a second DNS response packet according to the target domain name and the IP address corresponding to the target domain name, and sends the second DNS response packet to the network access apparatus; receiving, by the network access apparatus, the second DNS response packet sent by the DNS server, wherein the second DNS response packet comprises the target domain name and a second IP address, and the second IP address is an IP address that corresponds to the target domain name and that is recorded in the correspondence that is stored in the DNS server and that is between a domain name and an IP address; and sending, by the network access apparatus, the second DNS response packet to the UE.