Which two PHY modes are available to implement an IOS XR Gigabit Ethernet interface? (Choose two.)

SONET (Synchronous Optical Networking) is a high-speed optical transmission standard that can serve as a PHY mode (specifically, Gigabit Ethernet WAN PHY typically uses SONET/SDH framing) for Gigabit Ethernet interfaces in service provider networks.

MAN (Metropolitan Area Network) describes a network's geographical scope, not a physical layer mode for an interface.

WDM (Wavelength Division Multiplexing), often DWDM (Dense WDM), refers to optical technology used to carry multiple signals over a single fiber. While not a 'mode' like LAN/WAN PHY, DWDM-capable interfaces (e.g., DWDM PHY mode) are indeed available as specific physical layer options for high-speed Ethernet interfaces in IOS XR, indicating how the optical signal is handled.

LAN (Local Area Network) describes a network's geographical scope and is not a configurable PHY mode for a Gigabit Ethernet interface itself, though the interface operates in LANs.

WAN (Wide Area Network) describes a network's geographical scope, not a physical layer mode for an interface, although Gigabit Ethernet interfaces can operate over WANs.