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СКАЧАТЬ or xinetd that's listening for connections, option E omits the critical -p option, which causes the program to display process names. Thus, option E is incorrect. For more information, see Chapter 10, “Securing Your System.”

      3. D. The lpc utility is used to start, stop, change the priority of, and otherwise control jobs in a print queue. CUPS ships with an lpc utility, but it's quite rudimentary compared to the lpc utilities of BSD LPD and LPRng. Instead, CUPS relies on its Web-based interface to provide the ability to control print jobs. Thus, option D is correct, and the remaining options must logically all be incorrect. For more information, see Chapter 6.

      4. C. The /etc/security/limits.conf file defines various limits on user resources, including the number of simultaneous logins individual users are permitted. Thus, option C is correct. The /etc/pam.d/login-limits file (option A) is fictitious, although login limits do rely on the pam_limits module to the Pluggable Authentication System (PAM). The /etc/bashrc file (option B) is a global bash startup script file, but it's not normally used to impose login limits. The /etc/inittab file (option D) is a key Linux startup file, but it doesn't have any direct bearing on imposing login limits. The /etc/passwd file (option E) defines many key account features, but login limits are not among these. For more information, see Chapter 10.

      5. C, D. The computer's IP address (option C) and network mask (aka subnet mask or netmask; option D) are the most critical components in TCIP/IP network configuration. (Additional information that you may need to provide on many networks includes the IP addresses of one to three DNS servers, the hostname or IP address of a router, and the computer's hostname.) You shouldn't need the IP address of a Dynamic Host Configuration Protocol (DHCP) server (option A) – and if a DHCP server is present, chances are you should be using DHCP rather than static IP address assignment. A NetBIOS Name Service (NBNS) server (option B) converts between names and IP addresses on NetBIOS networks. The hostname of such a computer isn't likely to be a critical configuration element, although you may need to provide this information to Samba for some operations to function correctly when sharing files. A Network Time Protocol (NTP) server (option E) helps you maintain system time on all of your computers, but this isn't required for basic network configuration. For more information, see Chapter 8, “Configuring Basic Networking.”

      6. E. The wc command displays a count of newlines, words, and bytes in the specified file (report.txt). Piping this data through tee causes a copy of the output to be stored in the new file (wc in this example – you shouldn't run this command in the same directory as the wc executable file!). Thus, option E is correct. Contrary to option A, wc is not an editor, and the remaining syntax wouldn't cause two files to open in separate windows even if wc were an editor. Contrary to option B, wc doesn't count windows or open a new window. Option C describes the effect of wc report | wc– that is, it overlooks the tee command. Contrary to option D, wc has nothing to do with cleaning up memory leaks, and tee doesn't directly use the report.txt file. For more information, see Chapter 1, “Exploring Linux Command-Line Tools.”

      7. C. The grub.cfg filename indicates a GRUB 2 configuration file. In such files, each OS or kernel stanza begins with a menuentry line and an open curly brace ({) and ends with a close curly brace (}). Thus, option C is correct. Some configuration files and programming languages use semicolons (;) at the end of most lines, but this isn't true of GRUB 2, so option A is incorrect. Although close parentheses ()) are used to terminate some types of options in some configuration files, including disk identifiers in GRUB 2's configuration file, they aren't used to terminate whole OS or kernel definitions in this file, so option B is incorrect. The string */ terminates comments in C program files but isn't commonly used in GRUB 2 configuration files, so option D is incorrect. Option E would be correct if the question had asked about a GRUB Legacy configuration file (menu.lst or grub.conf), but the question specifies a GRUB 2 configuration file (grub.cfg); the two boot loaders terminate their OS/kernel stanzas differently, so option E is incorrect. For more information, see Chapter 5, “Booting Linux and Editing Files.”

      8. E. The third field of /etc/passwd entries holds the UID number for the account, so option E is correct. Linux doesn't use any standard identifier called a human ID (HID; option A), although the acronym HID stands for human interface device, a class of USB devices. Accounts don't have PID numbers (option B); those belong to running processes. The account's GID number (option C) is stored in the fourth field of /etc/passwd—100 in this example. Linux accounts don't use globally unique ID (GUID) numbers, so option D is incorrect. For more information, see Chapter 7, “Administering the System.”

      9. B. The grep command scans files to find those that contain a specified string or pattern, as described by option B. In the case of text files, grep displays the matching line or lines; for binary files, it reports that the file matches the pattern. The method of creating a pipeline (option A) involves separating two commands with a vertical bar (|). The grep command can be used in a pipeline, but it doesn't create one. The command that concatenates files (option C) is cat, and the command that displays the last several lines of a file (option D) is tail. Several commands, such as find, locate, and whereis locate files (option E), but grep is not among them. For more information, see Chapter 1.

      10. B, D, E. ReiserFS (option B) was written from scratch for Linux. The Third Extended Filesystem (ext3fs; option D) is a journaling filesystem based on the older non-journaling Second Extended Filesystem (ext2fs; option C). The Extents Filesystem (XFS; option E) is a journaling filesystem written by SGI for Irix and later ported to Linux. The Virtual File Allocation Table (vfat; option A) is a non-journaling filesystem designed by Microsoft for Windows. For more information, see Chapter 3, “Configuring Hardware.”

      11. A. Option A correctly describes the features of SSH and GPG in this context. Option B is incorrect because SSH should do a fine job of encrypting your email so that it can't be decoded between your system and your ISP's email server. Option C has it backward; email transferred via SSH will be completely encrypted, including both headers and body. GPG doesn't encrypt headers, just message bodies. Option D is incorrect because GPG isn't a virus scanner, just an encryption tool. Option E is incorrect because the SSH tunnel will encrypt everything in the SMTP transfer, including email attachments. For more information, see Chapter 10.

      12. A, D. Port 110 (option A) is assigned to the Post Office Protocol (POP), and port 143 (option D) is assigned to the Internet Message Access Protocol (IMAP), both of which may be used to retrieve email messages from an email server system. Port 119 (option B) is assigned to the Network News Transfer Protocol (NNTP), port 139 (option C) is assigned to the Server Message Block/Common Internet File System (SMB/CIFS) protocol, and port 443 (option E) is assigned to the Hypertext Transfer Protocol with SSL encryption (HTTPS), none of which is commonly used for email retrieval. For more information, see Chapter 8.

      13. C. Log files, such as /var/log/messages and sometimes others in /var/log, often contain useful information concerning server errors. The tail program displays the last few lines of a file, so using it to examine log files immediately СКАЧАТЬ