CCNP Interview Question:

Explain how a letter from New York City to San Diego is routed using the address information.

Submitted by: Administrator

The source address is not used unless the letter needs to be returned to the sender. Using the destination address, the access level post office in New York examines the state, city, and street information to determine if it is directly connected to the destination. If not, the letter is sent to the distribution layer post office using a default route. The distribution layer post office also examines the state, city, and street information to determine if it is directly connected to an access layer post office servicing the particular street. If it isn't, the letter is routed to the core level using a default route. The core level post office examines the state name, and if the state name does not equal New York, the letter is delivered to the core post office for the state of California. The California core post office delivers the letter to the distribution post office that handles the city of San Diego. The San Diego distribution post office delivers the letter to the access post office that handles the destination street. Finally, the access level switch delivers the letter to the proper destination.
Submitted by: Administrator