Alibaba Cloud intranets are classified into classic network and VPC. Cloud products (such as ECS and ApsaraDB for MongoDB) in the same region can establish cross-zone connection over an intranet. There are two scenarios of intranet-based cross-zone connection between ApsaraDB for MongoDB and ECS:
Connection between an ECS instance and a MongoDB instance that is bought in another zone of the same region as the ECS instance
If the ECS instance is a VPC instance, to connect the two instances over the intranet, make sure both instances have the same VPC ID and create a switch in the zone where the MongoDB instance is located.
If the ECS instance belongs to the classic type, to connect the two instances, make sure the MongoDB instance also belongs to the classic type.
Connection between an existing MongoDB instance and ECS instance
In the case that the ECS instance and MongoDB instance are located in the same region:
The two instances can establish connection over the intranet only if both instances belong to the same network type (which is classic or VPC; in the latter case, both instances must have the same VPC ID).
If the two instances belong to different network types, use the network type change function provided by ApsaraDB for MongoDB to change the network type of the MongoDB instance before you connect the two instances.