CompTIA® A+ Operating Systems Exam Notes : Viruses, Networking Utilities, Troubleshooting Tcp/ip
A+ Operating Systems Technologies(220-302) Exam Cram
A+ Certification, awarded by CompTIA® organization is the most widely recognized certification in the area of PC hardware and software technologies. To attain A+ certification, one need to pass 2 exams, namely, A+ Core Hardware Technologies, and A+ Operating Systems Technologies. These exams basically test the skills in assembling a computer, troubleshooting, and the ability to work with various operating systems.Linux is not included in the A+ Certification Operating Systems exam, as it has an exam of its own (Linux+ Certification),offered by CompTIA. The exam cram offers several final preparation points for candidates intending to appear for the A+ test. Latest objectives are available from Comptia.com website.
21. If Autoexec.bat tried to access a drive letter that is not valid, the error message "Current drive is no longer valid" appears.
- A boot sector virus stays resident by infecting the boot sector of the computer
- A Master boot record (MBR) virus infect the first physical sector of all affected disks
- File viruses either replace or attach themselves to executable files, and most commonly found virus.
- Macro virus attaches itself to documents in the form of macros.
- Memory viruses are viruses that execute and stay resident in memory. Trojan Horse is an example of memory virus.
- TCP/IP is the protocol used when you are Telnetting to a remote host. HTTP is used for accessing the World Wide Web services.
- SMTP is used to upload mail to the mail server. POP3 is used for downloading mail from a mail server to a client machine running POP3 client.
- Both PPP and SLIP can be used for dial up connections. However, SLIP can't be used where the IP address need to be assigned dynamically. The advantage of PPP is multi protocol support, that it can support TCP/IP, IPX, AppleTalk etc. SLIP can support only TCP/IP and IP addresses need to be assigned manually.
- WINS server resolves the NetBIOS names to IP addresses. A Windows network running TCP/IP need to be configured with WINS (or LMHOSTS file on each computer) for NetBIOS name resolution.
24. Networking utilities:
- NBTSTAT: This utility displays current NetBIOS over TCP/IP connections, and display NetBIOS name cache.
- NETSTAT: Displays protocol statistics and current TCP/IP connections since the server was last booted.
- TRACERT: Used to determine which route a packet takes to reach its destination from source.
- IPCONFIG: Used to display Windows IP configuration information.
- NSLOOKUP: This utility enables users to interact with a DNS server and display resource records.
- ROUTE: Used to display and edit static routing tables.
25. Some of the important commands useful in trouble shooting TCP/IP networks are:
- Ipconfig: Displays TCP/IP configuration values, including IP address, subnet mask, and default gateway.
- Ping: This command can be used to verify whether the target ip address or host name is present. You need to specify the target IP address or host name. You can ping the loop back address at 127.0.0.1. A response ensures that the TCP/IP stack is installed properly on your computer.
- Route: Displays and manipulates route information.
- Tracert: Determines the route packets take to reach the specified destination.
26. To see TCP/IP configuration on a Windows 95 / 98 computer, use WINIPCFG. It will display your IP address, subnet mask, default gateway, hardware MAC address.
To see TCP/IP configuration on an NT machine, use IPCONFIG. It will also display the IP configuration information on an NT machine. To get more details, use IPCONFIG/ALL
27. DLL stands for Dynamic Link Library. DLL is a special form of application code loaded into memory by request. A DLL is not executable by itself. More than one application may use the functions offered by a DLL.
28. HTML stands for Hyper Text Markup Language. HTML is the language most widely used for writing Web pages.
29. You can't apply file level permissions on a FAT file system. Only NTFS allows file permissions. Remember that the NTFS file permissions are always in effect to all users and processes.
30. PAP and CHAP:
- PAP uses 2-way handshaking. Passwords are sent in clear text across the link. Therefore, PAP is to be used only when it not possible to use CHAP.
- CHAP uses 3-way handshaking. CHAP uses Challenge/ Response method, that provides protection against the password capture while authenticating the user. One should use CHAP whenever it is possible.
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