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. com domain receives the request, it will find a management. com domain's next-level DNS server address (baidu.com) to the local DNS server if it cannot implement the resolution itself. When the local DNS server receives this address, it will find the baidu.com domain server, repeat the above 3,2,1 action to query until the www.baidu.com host is found.(5), the data is embedded in the TCP packet returned.4. TCP protocolThe TCP protocol embeds the port of the HTTP protocol in the packet and sends

; 2 in the second "show" in the bar, drag the slider to 15 minutes, that is, 15 minutes without action, the monitor off, If the impact of watching movies, can be dragged to the far right "never"; 3 and then click on the "General" label, look at the other settings, generally do not modify what, if you want to modify, remember what was originally; 4) Point "Off" button, the power and screensaver completed the settings; Ubuntu

Computer hardware can actually be more easily divided into CPU + memory +io devices. The three of them are through a bus to exchange data, and you know in the three CPU speed of the fastest, memory second, IO device third, to make the three coordination of communication requires a certain control. 2. our CPU has its own local bus, the same memory, the local bus through the motherboard of the South Bridge chip link together to communicate. North Brid

rint:]: Printable characters[: Cntrl:]: Control (nonprinting) character[: Graph:]: Graphic character[: Xdigit:]: hexadecimal characterInode,block,bitmapIndex node? The Inode (index node) table contains a list of all file system files? A node (an index node) is a table item that contains information about the file (metadata), including:File type, permissions, Uid,gidNumber of links (pointing to the number of path names for this file name)The size of the file and the different timestampsData bloc

and there is content to be overwritten)Add content echo >> file name (> Overwrite action)8 Delete Directory rmdir/q/s folder nameDelete File del file nameOptional parameters-S recursion-Q (quite) quiet-F (Force) mandatory9.move MobileIpconfig view IP addressPing Test network connectivity For example: Ping www.baidu.com12. Configure the Hosts file to bypass DNS resolution and directly look for IP addresses.Hosts file address C:\Windows\System32\drivers\etc\hostsUsage: Add directly to hosts ' Hos

operation is complete before returning, ensuring the reliability of the dataFdatasync: Data block synchronization for individual files. Wait until the disk operation is complete before returning, ensuring the reliability of the dataMsync: Synchronizing dirty pages generated by mmapThe page recycling mechanism consists of three parts, data brush out flush, swap swap, releasing release.Data brush flush and data synchronization are similar, that is, the backup file of the page cache is synchronize

1. Introduction1 What is data compression?Data compression reduces the amount of data sent or stored by partially eliminating the inherent redundancy in the data.Data compression improves the efficiency of data transfer and storage, while protecting the integrity of the database.2 Data compression methodThe data compression method is divided into lossless compression and lossy compression.Lossless compression is suitable for text or programs. lossy compression is suitable for images, video, and

Before learning about networks, review the basics of computer networks. Lu Xun said that there is a huge copy of the article in the world. If you have any questions, you can copy the book based on your basic knowledge. A layered model 1. Why Layer In order to simplify the network design complexity, communication protocols adopt a layered structure, and Protocols at different layers are mutually indepe

the new.3 Enter the command to edit the password.5 single-user mode hack password1 start the virtual user, and at the time of the Grub boot interface, select the startup item with the up and down keys.2 use ' e ' to enter the startup item of your choice, then use the up and down keys to move the cursor to "linux16 ...". "That line, delete" rhgb quiet, then use the end key to move the cursor to the tail of the character, add the parameter init=/bin/sh, to tell Grub to start the operating system,

The philosophical thought of LinuxEverything is a file (including hardware)Small, single-use programsLink programs to accomplish complex tasks togetherAvoid confusing user interfacesConfiguration data is stored in textDevelopment interface StandardABI (Application Binary Interface)Describes the underlying interface between the application and the OS;API (Application Programming Interface)Define the interface between the source code and the libraryPOSIX (Portable Operating System Interface)A seri

details are not the same, you can run different systemsApi:application Programming Interface Application Programming Interface (programmer)CPU Architecture Type:X86X64Armm68000,m68k MotorolaPower IBMPowerPC Apple Motorola IBM co-developmentUltraSPARC SUNAlpha HPItanium CompaqWindowsLinux:Linus→linuxGnu/linuxUnix:System: (Bell Lab)AIX (IBM)Solaris (SUN)HP-UX (Hewlett-Packard)BSD: (BSRG) Berkeley System distributionNetBSDOpenbsdFreebsdMit:richard StallmanGnu:gnu is not Unix:Gpl:general Public Lic

Assume is s a string of lower case characters.Write A program This prints the longest substring of in s which the letters occur in alphabetical order. For example, if s = ‘azcbobobegghakl‘ , then your program should printLongest substring in alphabetical order Is:begghIn the case of ties, print the first substring. For example, if s = ‘abcbcd‘ , then your program should printLongest substring in alphabetical order IS:ABC# Paste Your code into this boxCount = 1result = S[0]While S:Newcount = 1New