A computer-implemented method comprising: obtaining, by a client node of a first blockchain instance, a blockchain domain name of a second, different blockchain instance, wherein: each blockchain instance in a unified blockchain network has a respective blockchain domain name that is a unique identifier of the blockchain instance in the unified blockchain network, wherein the unified blockchain network comprises a plurality of blockchain instances, including the first blockchain instance and the second blockchain instance, that are communicatively linked by two or more relays; each blockchain domain name comprises a human-readable label; and each blockchain domain name uniquely corresponds to a chain identifier of the blockchain instance that the blockchain domain name uniquely identifies; identifying, by the client node, a chain identifier of the second blockchain instance based on the blockchain domain name of the second blockchain instance, wherein the chain identifier of the second blockchain instance indicates a blockchain network configuration of the second blockchain instance, and wherein the chain identifier of the second blockchain instance comprises a hash value of a genesis block of the second blockchain instance and a network identifier of the second blockchain instance; and accessing, by the client node, the second blockchain instance based on the blockchain network configuration indicated by the chain identifier of the second blockchain instance. obtaining, by a client node of a first blockchain instance, a blockchain domain name of a second, different blockchain instance, wherein: each blockchain instance in a unified blockchain network has a respective blockchain domain name that is a unique identifier of the blockchain instance in the unified blockchain network, wherein the unified blockchain network comprises a plurality of blockchain instances, including the first blockchain instance and the second blockchain instance, that are communicatively linked by two or more relays; each blockchain domain name comprises a human-readable label; and each blockchain domain name uniquely corresponds to a chain identifier of the blockchain instance that the blockchain domain name uniquely identifies; each blockchain instance in a unified blockchain network has a respective blockchain domain name that is a unique identifier of the blockchain instance in the unified blockchain network, wherein the unified blockchain network comprises a plurality of blockchain instances, including the first blockchain instance and the second blockchain instance, that are communicatively linked by two or more relays; each blockchain domain name comprises a human-readable label; and each blockchain domain name uniquely corresponds to a chain identifier of the blockchain instance that the blockchain domain name uniquely identifies; identifying, by the client node, a chain identifier of the second blockchain instance based on the blockchain domain name of the second blockchain instance, wherein the chain identifier of the second blockchain instance indicates a blockchain network configuration of the second blockchain instance, and wherein the chain identifier of the second blockchain instance comprises a hash value of a genesis block of the second blockchain instance and a network identifier of the second blockchain instance; and accessing, by the client node, the second blockchain instance based on the blockchain network configuration indicated by the chain identifier of the second blockchain instance.