Which two statements are true about IS - IS?（）

• A、Interfaces have a default metric of 1.
• B、Level 1 is intra - area and level 2 is interarea.
• C、Level 1 routing is between an end system (ES) and IS while Level 2 routing is between an IS and IS.
• D、Hosts send ISHs while routers send ESHs.
• E、IS - IS is an open standard.
• F、Metrics depend on interface speed.