A.報文 B.線路 C.信元 D.分組
A.141.0.0.0 B.3.3.3.3 C.197.234.111.123 D.23.34.45.56
A.數(shù)據(jù)鏈路層B.網(wǎng)絡層C.傳輸層D.物理層
