相关试题
【单选题】
4下列半导体材料哪一种的热敏性突出“导电性受温度影响最大”？___
A. 本征半导体
B. N型半导体质
C. P型半导体
【单选题】
5用万用表电阻挡检测某一个二极管时，发现其正、反电阻均近于1000KΩ，这说明该二极管是属于___。
A. 短路状态；
B. 完好状态；
C. 断路状态；
D. 极性搞错。
【单选题】
6稳压二极管是一个可逆击穿二极管，稳压时工作在___状态。
【单选题】
7三端集成稳压器CW7812的输出电压是___。
【单选题】
8三端集成稳压器CXX7805的输出电压是___
【单选题】
9一个平衡PN结，用导线将P区和N区连起来，而导线中___。
A. 有微弱电流
B. 无电流
C. 有瞬间微弱电流
【单选题】
10二极管两端正向电压大于___电压时，二极管才导通。
【单选题】
11当温度升高时，二极管的反向饱和电流 ___ 。
A. 增大；
B. 减小；
C. 不变；
D. 无法判定。
【单选题】
12硅二极管的正向导通压降比锗二极管的___ 。
【单选题】
13三端集成稳压器 CW7906的输出电压是___
【单选题】
14稳压管的工作是利用伏安特性中的___。
A. 正向特性
B. 反向特性
C. 反向击穿特性
【单选题】
15二极管具有___
A. 正向特性
B. 反向特性
C. 单向导电特性
D. 反向击穿特性
【单选题】
16图中D1-D3为理想二极管，A，B，C灯都相同，试问___灯最亮。
【单选题】
18在单相桥式整流电容滤波电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
19在单相桥式整流电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
20在半波整流电容滤波电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
21在半波整流电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
22温度影响了放大电路中的___，从而使静态工作点不稳定。
A. 电阻；
B. 电容；
C. 三极管；
D. 电源。
【单选题】
23用直流电压表测得放大电路中某三极管各极电位分别是2V、6V、2.7V，则三个电极分别是___。
A. [B、C、E]
B. [C、B、E]
C. [E、C、B]
【单选题】
24共射极放大电路的交流输出波形上半周失真时为___
【单选题】
25三极管的反向电流ICBO是由___组成的。
A. 多数载流子
B. 少数载流子
C. 多数载流子和少数载流子
【单选题】
27如果在NPN型三极管放大电路中测得发射结为正向偏置，集电结也为正向偏置，则此管的工作状态为___
A. 放大状态；
B. 截止状态；
C. 饱和状态；
D. 不能确定。
【单选题】
28在以下三种电路中输入电阻最大的电路是___。
A. 共基放大电路
B. 共集放大电路
C. 共射放大电路
【单选题】
29在以下三种电路中既能放大电流，又能放大电压的电路是___。
A. 共基放大电路
B. 共集放大电路
C. 共射放大电路
【单选题】
30在以下三种电路中输出电阻最小的电路是___；
A. 共基放大电路
B. 共集放大电路
C. 共射放大电路
【单选题】
当PNP型晶体管工作在放大区时，各极电位关系为uC ___uB。
【单选题】
32当PNP型晶体管工作在放大区时，各极电位关系为uB___uE 。
【单选题】
33测得NPN型三极管上各电极对地电位分别为，，，说明此三极管处在___。
A. 放大区
B. 饱和区
C. 截止区
D. 反向击穿区
【单选题】
34若使三极管具有电流放大能力，必须满足的外部条件是___。
A. 发射结正偏、集电结正偏
B. 发射结反偏、集电结反偏
C. 发射结正偏、集电结反偏
D. 发射结反偏、集电结正偏
【单选题】
35在由PNP晶体管组成的基本共射放大电路中，当输入信号为1KHz、5mV的正弦电压时，输出电压波形出现了顶部削平的失真。这种失真是___ 。
A. 饱和失真
B. 截止失真
C. 交越失真
D. 频率失真
【单选题】
36在由PNP晶体管组成的基本共射放大电路中，当输入信号为1KHz、5mV的正弦电压时，输出电压波形出现了底部削平的失真。这种失真是___ 。
A. 饱和失真
B. 截止失真
C. 交越失真
D. 频率失真
【单选题】
37共集电极放大电路中Re的负反馈组态是___。
A. 电压串联负反馈
B. 电流串联负反馈
C. 电压并联负反馈
【单选题】
38为了使放大器带负载能力强，一般引入___负反馈。
【单选题】
41为了提高三极管放大电路的输入电阻，采用___负反馈 i=i1+i2
【单选题】
42为了稳定输出电流，采用___负反馈。
【单选题】
43为了改善放大器的动态性能，应该引入___电路。
A. 直流负反馈
B. 交流负反馈
C. 电压负反馈
D. 电流负反馈
【单选题】
44为了稳定放大器的静态工作点，应该引入___电路。
A. 直流负反馈
B. 交流负反馈
C. 电压负反馈
D. 电流负反馈
【单选题】
45共模抑制比是差分放大电路的一个主要技术指标，它反映放大电路___能力。
A. 放大差模抑制共模
B. 输入电阻高
C. 输出电阻低
【单选题】
46差分放大电路是为了___而设置的。
A. 稳定Au
B. 放大信号
C. 抑制零点漂移
【单选题】
47分析运放的“虚短”是指是___。
A. U-≈U+
B. I-≈I+≈0
C. U0=Ui
D. U-≈U+≈0
推荐试题
【单选题】
How can you mitigate attacks in which the attacker attaches more than one vLan tag to a packet？___
A. Assign an access VLAN to every active port on the switch
B. Disable Ether Channel on the switch
C. Explicitly identity each VLAN allowed across the trunk
D.
E. nable transparent VTP on the switch
【单选题】
Which technology can you implement to centrally mitigate potential threats when users on your network download files that might be malicious？___
A. Enable file-reputation services to inspect all files that traverse the company network and block files with low reputation scores
B. Verify that the compa ny IpS blocks all known malicious website
C. Verity that antivirus software is installed and up to date for all users on your network
D. Implement URL filtering on the perimeter firewall
【单选题】
What is the most common implementation of PaT in a standard networked environment？___
A. configuring multiple external hosts to join the self zo ne and to communicate with one another
B. configuring multiple internal hosts to communicate outside of the network using the outside interface IP address
C. configuring multiple internal hosts to communicate outside of the network by using the inside interface IP address
D. configuring an any any rule to enable external hosts to communicate inside the network
【单选题】
Which component of a bYod architecture provides aAa services for endpoint access ?___
A. Integrated Services Router
B. access point
C. ASA
D. Identity Services
E. ngine
【单选题】
You are configuring a NAT rule on a Cisco ASA ,Which description of a mapped interface is true?___
A. It is mandatory for all firewall modes
B. It is optional in routed mode
C. It is optional in transparent mode
D. It is mandatory for ide ntity NAT only
【单选题】
Which description of the use of a private key is true ？___
A. The sender signs a message using the receivers private key
B. The sender signs a message using their private key
C. The sender encrypts a message using the receivers private key
D. The receiver decrypts a n15ssage using the sender's private key
【单选题】
Which mechanism does the FireAMP Connector use to avoid conflicts with other security applications such as antivirus products ?___
A. Virtualization
B. Containers
C. Sandboxing
D.
E. xclusions
【单选题】
Which network to pology de scribes multiple LANS in a gec? ___
A. SOHO
B. MAN
C. pan
D. CAN
【单选题】
Which statement represents a difference between an access list on an aSa versus an access list on a router？___
A. The asa does not support number access lists
B. The aSa does not support standard access list
C. The asa does not ever use a wildcard mask
D. The asa does not support extended access lists
【单选题】
Which command do you enter to verify the status and settings of an iKE Phase 1 tunnel？___
A. show crypto ipsec as output
B. show crypto isakmp
C. show crypto isakmp policy
D. show crypto ipsec transform
【单选题】
Which feature can help a router or switch maintain packet forwarding and protocol states despite an attack or heavy traffic load on the router or switch？___
A. service Policy
B. Control Plane Policing
C. Policy Map
D. Cisco
E. xpress
F. orwarding
【单选题】
Which STP feature can prevent an attacker from becoming the root bridge by immediately shutting down the interface when it receives a BPDU？___
A. root guard
B. Port Fast
C. BPDU guard
D. BPDU filtering
【单选题】
Which technology can best protect data at rest on a user system？___
A. full-disk encryption
B. IPsec tunnel
C. router ACL
D. network IPS
【多选题】
Which two primary security concerns can you mitigate with a BYOD solution ？___
A. schedule for patching the device
B. securing access to a trusted corporate network
C. compliance with applicable policies
D. connections to public Wi-Fi networks
E. device tagging and invento
【多选题】
choose five___
A. MD5————————inserure
B. DES————————insercure
C. SDES———————legacy
D. SHA-1———————legacy
E. HMAC-MD5—————legacy
【多选题】
Which two characteristics of symmetric encryption are true？___
A. It uses digital certificates
B. It requires more resources than asymmetric ancryption
C. It uses the same key to enctypt and decrupt traffic
D. It uses a public key and a pricate key to encrypt and decrypt traffic.
E. It is faster than asymmetric encryption
【多选题】
which two characteristics of PVLAN are true？___
A. Promiscuous porta can communicate with PVLAN ports.
B. Isolated ports cannot communicate with other ports on the same VLAN
C. Community ports have to be a part of the trunk.
D. They require VTP to be enabled in server mode
E. PVLAN ports can be configured as Ether Channel ports
【多选题】
What are two options for running Cisco SDM?___
A. Running SDM from a mobile device
B. Running SDM from within CiscoWorks
C. Running SDM from a router's flash
D. Running SDM from the Cisco web porta
E. Running SDM from a PC
【多选题】
Which two options are the primary deployment modeles for mobile device management？___
A. multisite
B. cloud-based
C. on premises
D. hybrid cloud basedo
E. single site
【多选题】
Drag the recommendation on the left to the Cryptographic algorithms on the right， Options will be used more than once.___
A. Avoid——————————————DES，MD5
B. Legacy——————————————SDES，SHA1，HMAC-MD5
【多选题】
Which two are valid types of vLans using PVLANS ?___
A. Community VLAN
B. Backup VLAN
C. Secondary VLAN
D. Isolated VLAN
E. Isolated VLAN
【多选题】
Which two commands are used to implement Resilient lOS Configuration ___
A. Secure boot-config
B. copy running-config tftp
C. copy flash:ios bin tftp
D. copy running-config startup-config
E. secure boot-image
【多选题】
Which two types of firewalls work at layer 4 and above ？___
A. Stateful inspection
B. Network Address Translation
C. Circuit-Level gateway
D. Static packet filter
E. Application Level firewall
【多选题】
Which two default settings for port security are true ？___
A. Violation is Protect
B. Violation is Restrict
C. Violation is Shutdown
D. Maximum number of MAC addresses is 2
E. Maximum number of MAC addresses is 1
【多选题】
Which two are characteristics of RADIUS？___
A. Uses UDP ports 1812 /1813
B. Uses TCP port 49
C. Uses UDP port 49
D.
E. ncrypts only the password between user and server
【多选题】
When setting up a site-to-site VPN with PSK authentication on a Cisco router， which two elements must be configured under crypto map？___
A. pfs
B. nat
C. reverse route
D. peer
E. transform-set
【多选题】
When using the Adaptive Security Device Manager（ASDM), which two options are available to add a new root certificate？___
A. Install from SFTP server
B. Usehttps
C. Install from a file
D. Use LDAP
E. Use SCEP
【多选题】
Which two SNMPv3 services support its capabilities as a secure networ k manage protocol？ ___
A. access control
B. the shared secret key
C. authentication
D. authorization
E. accounting
【多选题】
Which two statements about routed firewall mode are true ？___
A. The firewall acts as a routed hop in the network
B. This mode conceals the presence of the firewall
C. The firewall requires a unique iP address for each interface
D. This mode allows the firewall to be added to an existing networ k with minimal additional configuration By default， this mode permits most traffic to pass throug
【多选题】
Which two statements describe DHCP spoofing attacks？___
A. They are used to perform man-in- the-middle attacks
B. They can access most network devices
C. They can modify the flow of traffic in transit. LNGKAIG
D. They protect the identity of ti attacker by masking the DHCP address
E. They can physically modify the network gateway
【多选题】
Which two types of VLANs using PVLANs are valid？___
A. isolated
B. promiscuous
C. backup
D. secondary
E. community
【多选题】
What are two limitations of the self-zone policies on a zone-based firewall？___
A. They are unable to block Https traffic
B. They restrict SNMP traffic.
C. They are unable to support Https traffic
D. They are unable to implement application inspection
E. They are unable to perform rate limiting
【多选题】
Which two descriptions of TACACS+ are true？ ___
A. The TACACS+ header is unencrypted
B. It combines a uthentication and authorization
C. It uses TCP as its transport protocol
D. Only the password is encrypted.
E. It uses UDP as its transport protocol.
【多选题】
Which two actions does an IPS perform？ ___
A. it spans the traffic
B. it reflects the traffic back to the sender
C. it encrypts the traffic
D. it terminates the user session or connection of the attacker
E. it reconfigures a device to block the traffic
【多选题】
In which form of fraud does an attacker try to learn information such as login credenti account information by ma squerading as a reputable entity or person in email， IM or communication channels ?___
A. phishing
B. Smurfit
C. Hacking
D. Identity Spoofing
【多选题】
Which two ESA services are available for incoming and outgoing mails ？___
A. anti-DoS
B. reputation filter
C. antispam
D. content filter
E. DLP
【多选题】
What are two reasons to recommend SNMPv 3 over SNMPv2？___
A. SNMPv3 is secure because you can configure authe ntication and privacy
B. SNMPv3 is insecure because it send in formation in clear text
C. SNMPv2 is insecure because it send information in clear text
D. SNMPv3 is a Cisco proprietary protocol
E. SNMPv2 is secure because you can configure authentication and privacy
【多选题】
Which two actions can a zone- based firewall apply to a packet as it transits a zone pair？___
A. drop
B. inspect
C. queue
D. quarantine
【单选题】
Which security principle has been violated if data is altered in an unauthorized manner？___
A. accountability
B. confidentiality
C. availability
D. integrity
【单选题】
Which IKE Phase 1 parameter can you use to require the site-to-site VPN to use a pre-shared ？___
A. encryption
B. authentication
C. group
