# IP addresses for Single Engine interfaces

You can define several types of IP addresses for the Single Engine's interfaces.

The interfaces of a Single Engine can have the following types of IP addresses:

- Each layer 3 physical interface can have one or more static or dynamic IP addresses. A layer 3 physical interface can have multiple dynamic IP addresses only if you add VLAN interfaces and the VLAN interfaces each have a dynamic IP address. Otherwise, a layer 3 physical interface can only have a single dynamic IP address. The same interface can have both IPv4 and IPv6 addresses.
- Each Aggregated Link interface can have one or more static IP addresses. The same interface can have both IPv4 and IPv6 addresses.
- Each VLAN interface can have one or more static IP addresses or a single dynamic IP address. The same interface can have both IPv4 and IPv6 addresses.
- Each SSID interface defined for the optional Wireless interface can have a single IPv4 or IPv6 address.
- A Tunnel interface can have one or more static IP addresses.
- A Port Group interface of an integrated Switch can have one or more static IP addresses or a single dynamic IP address. The same interface can have both IPv4 and IPv6 addresses.

Note: You cannot add IP addresses to layer 2 physical interfaces.

You might need to define a contact address if you enter a private static address and NAT is used to translate it to a different external IP address. The external IP address must be configured as the contact address if other SMC components must use the external IP address to contact this Engine or if the IP address is used as a VPN endpoint.

To use the engine as an IGMP proxy for multicast routing, the IP addresses for the downstream interfaces must be the lowest IP addresses among all IGMP queries in the local networks.