【单选题】
采用脉宽调制（PWM）进行直流电动机调速驱动时，通过改变 来改变电枢回路的平均电压，从而实现直流电动机的平滑调速 ___
A. 脉冲的宽度
B. 脉冲的频率
C. 脉冲的正负
D. 其他参数
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相关试题
【单选题】
光栅传感器的光栅是在一块长条形的光学玻璃上密集等间距平行的刻线，刻线数为 100 线/mm，此光栅传感器测量分辨率是 mm ___
A. 0.01
B. 0.1
C. 1
D. 0.001
【单选题】
多级齿轮传动中，各级传动比相等的分配原则适用于按 设计的传动链 ___
A. 重量最轻原则（小功率装置）
B. 输出轴的转角误差最小原则
C. 最小等效转动惯量原则
D. 重量最轻原则（大功率装置）
【单选题】
闭环控制的驱动装置中，丝杠螺母机构位于闭环之外，所以它的 ___
A. 回程误差和传动误差都不会影响输出精度
B. 传动误差不影响输出精度，但回程误差影响输出精度
C. 回程误差不影响输出精度，但传动误差影响输出精度
D. 回程误差和传动误差都会影响输出精度
【单选题】
C.改变电压的相位 D.改变电动机转子绕组匝数 12226.执行元件：能量变换元件，控制机械执行机构运动，可分为 、液压式和气动式等 ___
A. 电气式
B. 电磁式
C. 磁阻式
D. 机械式
【单选题】
在电力系统中，发电机的容量和变压器的容量一般呈现出一种 的关系 ___
A. 变压器的容量大于发电机容量
B. 几乎是相等的局面
C. 发电机容量大于变压器容量
D. 不能确定
【单选题】
所谓对称三相负载就是 ___
A. 三相负载阻抗值相等，且阻抗角相等
B. 三个相电压相等且相位角互差 120°
C. 三个相电流有效值相等，三个相电压相等且相位角互差 120°
D. 三个相电流有效值相等
【单选题】
交流电流 I 通过某电阻，在一定时间内产生的热量，与某直流电流 I 在相同时间内通过该电阻所产生的热量相等，那么就把此直流电流 I 定义为交流电流 i 的 ___
A. 有效值
B. 最大值
C. 最小值
D. 瞬时值
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【单选题】
Which command successfully creates an administrative user with a password of "cisco"on a Cisco router?___
A. username Operator privilege 7 password cisco
B. username Operator privilege 1 password cisco
C. username Operator privilege 15 password cisco
D. username Operator password cisco privilege 15
【单选题】
Which EAP method authenticates a client against Active Directory without the use of client-side 802.1X certificates？___
A. EAP-TLS
B. EAP-MSCHAPv2
C. EAP-PEAP
D.
E. AP-GTC
【单选题】
What is a limitation of network-based IPS？___
A. It must be in dividually configured to support every operating system on the network.
B. It is most effective at the in dividual host level
C. It is unable to monitor attacks across the entire netw ork
D. Large installations require numerous sensors to fully protect the network
【单选题】
When would you configure the ip dhcp snooping trust command on a sw itch？___
A. when the switch is connected to a DHCP server
B. when the switch is working in an edge capacit
C. when the switch is connected to a client system
D. when the switch is serving as an aggregator
【单选题】
How does the 802. 1x supplicant communicate with the authentication server？___
A. The supplicant creates EAP packets and sends them to the authenticator, which encapsulates them into RADIUS and forwards them to the authentication server.
B. The supplicant creates RADIUS packets and sends them to the authe nticator, which encapsulates the m into EAP and forwards them to the a uthentication server.
C. The supplicant creates RADIUS packets and sends them to the authenticator, which translates them into eap and forwards them to the a ut hentication server
D. The supplicant creates
E. AP packets and sends them to the authe nticator, which translates them into radius and forwards them to the authentication server.
【单选题】
Which command do you enter to verify the phase I status of a VPN connection？___
A. sh crypto se ssion
B. debug crypto isakmp
C. sh crypto isakmp sa
D. sh crypto ipsec sa
【单选题】
Refer to the exhibit. what is the e ffect of the given configuration？___
A. It enables authentication，
B. It prevents keychain authentication.
C. The two routers receive normal updates from one another.
D. The two device s are able to pass the message digest to one another.
【单选题】
Which command can you enter to configure OSPF to use hashing to authenticate routing updates？___
A. ip ospf aut hentication message-digest
B. neighbor 192 168.0 112 cost md5
C. ip ospf priority 1
D. ip ospf aut hentication-key
【单选题】
Which command can you enter to verify the status of Cisco lOS Resilient Configuration on a Cisco router?___
A. show secure bootset
B. secure boot-image
C. show binary file
D. ure boot-config
【单选题】
A user on your network inadvertently activates a botnet program that was received as an emai attachment. Which type of mechanism does Cisco Firepower use to detect and block only the botnet attack？___
A. network-based access control rule
B. reputation-based
C. user-ba sed access control rule
D. botnet traffic filter
【单选题】
What does the policy map do in CoPP？___
A. defines service parameters
B. defines packet selection parameters
C. defines the packet filter
D. define s the action to be performed
【单选题】
How is management traffic isolated on a Cisco ASR 1002？___
A. Traffic isolation is done on the vlan level
B. There is no management traffic isolation on a Cisco ASR 1002
C. Traffic is isolated based upon how you configure routing on the device
D. The management interface is configured in a special vRF that provides traffic isolation from the default routing table
【单选题】
Which statement about NaT table evaluation in the asa is true？___
A. After-auto NAT polices are appl d first
B. Manual NAT policies are applied first
C. the asa uses the most specific match
D. Auto NAT policies are applied first
【单选题】
Which information can you display by executing the show crypto ipsec sa command？___
A. ISAKMP SAs that are established between two peers
B. recent changes to the IP address of a peer router
C. proxy infor mation for the connection between two peers
D. IPsec SAs established between two peers
【单选题】
How can you prevent NAT rules from sending traffic to incorrect interfaces？___
A. Assign the output interface in the NAT statement
B. Add the no-proxy-arp command to the nat line.
C. Configure twice NAT instead o bject NAT. 5
D. Use packet-tracer rules to reroute misrouted NAT entries.
【单选题】
What term can be defined as the securing， control， and identification of digital data？___
A. cryptography
B. crypto key
C. cryptoanalysis
D. cryptology
【单选题】
Which feature in the dNS security module provide on and off network DNS protection？___
A. Data Loss Prevention
B. Umbrella
C. Real-time sandboxing
D. Layer-4 monitoring
【单选题】
Which a dverse consequence can occur on a network without BPDu guard ?___
A. The olde st switch can be elected as the root bridge
B. Unauthorized switches that are connected to the network can cause spanning-tree loops
C.
D. ouble tagging can cause the switches to experience CAM table overload.
【单选题】
What configuration is required for multitenancy ?___
A. shared infrastructure
B. multiple carriers
C. co-located resources
D. multiple separate zones
【单选题】
Why does ISE require its own certificate issued by a trusted CA？___
A. ISEs certificate allows guest devices to validate it as a trusted network device
B. It generates certificates for guest devices ba sed on its own certificate
C. It requests certificates for guest devices from the Ca server based on its own certificate.
D. ISE's certificate allows it to join the network security framework
【单选题】
which attack involves large numbers of ICMP packets with a spoofed source IP address？___
A. smurf attack
B. Teardrop attack
C. Nuke attack
D. SYN Flood attack
【单选题】
Which statement about interface and global access rules is true？___
A. Interface access rules are processed before global access rules.
B. Global access rules apply only to outbound traffic， but interface access rules can be applied in either direction
C. The implicit allow is proce ssed after both the global and interface access rules
D. If an interface access rule is applied， the global access rule is ignored
【单选题】
Which type of malicious software can create a back-door into a device or network？___
A. bot
B. worm
C. virus
D. Trojan
【单选题】
Which security term refers to the like lihood that a weakness will be exploited to cause damage to an asset？___
A. threat
B. risk
C. countermeasure
D. vulnerability
【单选题】
Which IPS detection method examines network traffic for preconfigured patterns？___
A. signature-based detection
B. honey-pot detection
C. anomaly-based detection
D. policy-based detection
【单选题】
What is an advantage of split tunneling ？___
A. It allows users with a VpN connection to a corporate network to access the internet with sending traffic across the cor porate network.
B. It allows users with a vpn connection to a corporate network to access the internet by using the vPN for security.
C. It protects traffic on the private network from users on the public network
D. It enables the VPN server to filter traffic more efficiently
【单选题】
Which IDS/IPS state misidentifies acceptable behavior as an attack ？___
A. false negative
B. true positive NEKA G
C. true negative
D. false positive
【单选题】
What is the maximum num ber of methods that a single method list can contain？___
A. 4
B. 3
C. 2
D. 5
【单选题】
Which command enables authentication at the oSPFv2 routing process level？___
A. ip ospf authentication message-digest
B. area 0 authentication message-digest
C. ip ospf message-digest-key 1 mds Cisco
D. area 0 authentication ipsec spi 500 md5 1234567890ABCDEF1234567890ABCDEF
【单选题】
Which type of firewall monitors a nd protects a specific system？___
A. firewall
B. application firewall
C. stateless firewall wvp
D. personal firewall
【单选题】
On an ASA， which maps are used to identify traffic？___
A. Route maps
B. Policy maps
C. Class maps
D. Service maps
【单选题】
Which type of social engineering attack targets top executives？___
A. whaling
B. vishin
C. spear phishing ng
D. baiting
【单选题】
What is the minimum Cisco lOS version that supports zone-based firewalls？___
A. 12.1T
B. 15.1
C. 15.0
D. 124
【单选题】
In which type of attack does an attacker overwrite an entry in the CAM table to divert traffic destined to a legitimate host？___
A. DHCP spoofing
B. ARP spoofing
C. CAM table overflow
D. MAC spoofing
【多选题】
Which two attack types can be prevented with the impleme ntation of a Cisco IPS solution？___
A. DDos
B. man-in-the-middle
C. worms
D. ARP spoofing
E. VLAN hopping
【多选题】
choose four___
A. DHCP snooping ——————————blocks DHCP messages
B. Dynamic ARP inspection——————verifies IP-to-MAC traffic on untrusted ports
C. IP sources guard ——————————provides layer 2 interface security with ports ACLs
D. Port security————————————mitigates MAC-address spoofing at the access interface
【多选题】
choose four___
A. Step1————————run the system setup wizard
B. Step2————————add an authentication realm
C. Step3————————configure identity management
D. Step4————————configure directory group
【多选题】
What are two advanced features of the Cisco AMp solution for endpoints ___
A. contemplation
B. foresight
C. sandboxing
D. reputation
E. reflection
【多选题】
Which two characteristics of RADIUS are true？___
A. It encrypts only the password between user and server.
B. It uses TCP ports 1812/1813
C. It uses UDP ports 1812/1813.
D. It uses UDP port 49
E. It uses TCP port 49
【多选题】
What are two challenges of using a network-based IPS？ ___
A. It is unable to determine whether a detected attack was successful
B. It requires additional storage and proce ssor capacity on syslog servers
C. As the network expands， it requires you to add more sensors.
D. It is unable to detect attacks across the entire network
E. It must support multiple operating systems.
