Cloud resource addresses
Addresses in cloud networks can be internal or public.
Internal IP addresses are assigned to resources in the selected subnet of the folder where the resource is created. These addresses are used for transmitting information between the resources within your cloud.
An internal IP address can only be used to access resources connected to subnets in the same cloud network. The internal IP address does not change during the entire lifetime of the cloud resource.
You can set internal IP addresses manually or automatically when creating a resource.
You can get a list of internal IP addresses that use cloud resources in the same subnet. For more information, see Viewing a list of addresses used in a subnet.
Public IP addresses allow cloud resources to exchange data with the internet and resources from other cloud networks. Public addresses are mapped to internal resource addresses using one-to-one NAT. You can assign public addresses to resources automatically or select them from the list of reserved addresses.
Public IP addresses can be dynamic or static. When creating a cloud resource with a public IP, it's usually assigned a dynamic address. When a VM with a dynamic public IP is stopped, its address is released, and the next time the VM is started, it is assigned a new public IP address. When the VM is restarted, its public IP address is saved.
You can make a dynamic public IP address static. Static IP addresses do not change when resources are stopped and you can reserve them in your folder for future use even if they aren't linked to any cloud resources. To learn how to make a dynamic IP address static, see Converting a VM's public IP address to static.
For more information about IP address pricing, see Public IP addresses in the Virtual Private Cloud documentation.
Outgoing traffic from TCP-port 25
Yandex Cloud always blocks outgoing traffic from Virtual Private Cloud public IP addresses to TCP port 25 of any servers on the internet (except for Yandex Mail servers) and Yandex Compute Cloud VMs.
Yandex Cloud may open TCP port 25 by request via technical support if you comply with Acceptable Use Policy. Yandex Cloud is entitled to block outgoing traffic on TCP port 25 if you violate the Use Policy.
You can use a hostname to access one cloud resource from another within the same cloud network.
The hostname is either set manually or generated automatically using the VM ID.
For more information about how FQDNs are generated, see Hostname and FQDN in the Compute Cloud documentation.