To ensure high availability and fault tolerance in a distributed hash table (DHT) network, it is recommended to use multiple nodes. Here's how you can achieve this:

1. Set up multiple nodes in the DHT network, each running on a separate machine or server.
2. Assign a unique sequence number to each node, with the first node having the highest sequence number. This ensures that the first node becomes the primary node in the DHT network.
3. In case the primary node goes offline, the next node with the highest sequence number will automatically become the new primary node, ensuring continuous operation of the DHT network.
4. To ensure seamless operation, all nodes should publish the same IPNS (InterPlanetary Name System) names. IPNS allows you to create a mutable mapping from a name to an IPFS (InterPlanetary File System) address. By publishing the same IPNS names on all nodes, you ensure that any node can serve the content associated with those names.
5. It's important to note that there is no built-in syncing mechanism in IPFS, so you need to manually publish the IPNS names on all nodes. This can be done using the ipfs name publish command.

By following these guidelines, you can achieve a robust and fault-tolerant DHT network with multiple nodes.