第67題： 數(shù)據庫系統(tǒng)是一個復雜性高的基礎性軟件，其安全機制主要有標識與鑒別、訪問控制、安全審計、數(shù)據加密、安全加固、安全管理等，其中( )可以實現(xiàn)安全角色配置、安全功能管理
A．訪問控制
B．安全審計
C．安全加固
D．安全管理
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第68題： 交換機是構成網絡的基礎設備，主要功能是負責網絡通信數(shù)據包的交換傳輸。其中工作于 OSI 的數(shù)據鏈路層，能夠識別數(shù)據中的 MAC，并根據 MAC 地址選擇轉發(fā)端口的是()
A．第一代交換機
B．第二代交換機
C．第三代交換機
D．第四代交換機
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第69題： 以下不屬于網絡設備提供的 SNMP 訪問控制措施的是( )。
A．SNMP權限分級機制
B．限制 SNMP 訪問的IP 地址
C．SNMP 訪問認證
D．關閉 SNMP 訪問
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第71題： Perhaps the most obvious difference between private-key andpublic-key encryption is that the former assumes complete secrecyof all cryptographic keys, whereas the latter requires secrecy foronly the private key.Although this may seem like a minor distinction ,the ramifications are huge: in the private-key setting thecommunicating parties must somehow be able to share the (71) keywithout allowing any third party to learn it, whereas in the public-key setting the (72) key can be sent from one party to the other overa public channel without compromising security.For partiesshouting across a room or, more realistically , communicating overa public network like a phone line or the nternet, public-keyencryption is the only option.
Another important distinction is that private-key encryption schemesuse the (73) key for both encryption and decryption, whereas publickey encryption schemes use (74) keys for each operation.That is public-key encryption is inherently asymmetri C．This asymmetry in thepublic-key setting means that the roles of sender and receiver are notinterchangeable as they are in the private-key setting; a single key-pair allows communication in one direction only.(Bidirectionalcommunication can be achieved in a number of ways; the point is thata single invocation of a public-key encryption scheme forces adistinction between one user who acts as a receiver and other userswho act as senders.)ln addition, a single instance of a (75) encryptionscheme enables multiple senders to communicate privately with asingle receiver,in contrast to the private-key case where a secret keyshared between two parties enables private communication onlybetween those two parties.
(1) A．main
B．same
C．public
D．secret
(2) A．stream
B．different
C．public
D．secret
(3) A．different
B．same
C．public
D．private
(4) A．different
B．same
C．public
D．private
(5) A．private-key
B．public-key
C．stream
D．Hash
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