Explain one of the procedures for HTTP access to Web server----The most basic steps __web

STEP 1: The process of connecting locally to your remote Web server

1.1) process of domain name resolution

The basic way the Web works----from entering the domain name in the browser to the user seeing the page content. First, the client (that is, your local computer) entered the domain name, the request for Domain name Resolution---> It will first send a request to the local domain name resolution server---> local domain name Resolution server first query its accumulated cache, if it has this domain name cache information, The cached content is returned directly to the requesting client. If there is no record in the local cache, the local domain name server sends the request to the root name server and the root name server tells it the address of the primary name server of the domain (the root subdomain) of the query, which is called the local name server to ask it, and the local server will send the request to the primary domain server. After the primary domain server accepts the request, it will also inquire about its own cache of the domain name, and if so, send the content directly to the local domain name server. If the primary name server does not have this domain name cache, it will give the local name server a subordinate domain name server address (primary name server subordinate), so always from the top to bottom of the query, finally get the correct record of the domain name, the local name server will keep this record as a cache, and send a query result about the domain name to the local client. The process of domain name resolution is explained in detail later in this article. Here is a typical example:

When the customer accesses www.baidu.com, if his local DNS server is dns.company.com, a root name server is NS.INTER.NET (about the root name server, should be the domain name of the network site is located server, to be queried again) , the domain name server of the website to be visited is dns.baidu.com, then the process of domain name resolution is as follows:

(1) The client makes a request to resolve the message (Information/request) of the domain name www.baidu.com, the local domain name server accepts the request, queries its cache, and if so, sends it back directly to the client. Assume that the local domain name server dns.company.com sends a request to NS.INTER.NET to resolve the www.baidu.com domain name.

(2) The root name server receives the request after the query local record obtains the result: Baidu.comns dns.baidu.com (indicates that the DNS server in the baidu.com domain is: dns.baidu.com), At the same time, the dns.baidu.com address is given, and the local domain name server will send a request to dns.baidu.com to resolve the domain name after receiving the message returned by the root name server.

(3) Dns.baidu.com after receiving the request, the local records are queried to find such a record: Www.baidu.com a 211.120.3.12, which indicates that the domain name server in the baidu.com domain dns.baidu.com the web The server IP address is 211.120.3.12 and returns the result to the local domain name server: dns.company.com. It saves the returned results to the local cache and informs the client of the results.

The above is a relatively smooth domain name resolution process.

Note: When you go to a domain name without www, if the return code of the Web server is 200, then the display connection is normal and you can communicate. Return code is 301, it shows that the domain has done 301 redirects, how to see if a site has done 301, then through the Webmaster tools---> Other tools--->http status query.

The domain name can be able to go to the normal parsing is a necessary condition, the domain name can be normal parsing, is the browser through the domain name can go to find the corresponding Web server IP (the domain name of a record), as to whether you can smooth access, there are a series of questions:

The ability to effectively detect commands from your local to Web server for unobstructed networks is also a requirement for access to a site.

Ping command as a tool to effectively detect the connection of a record from your local computer to your domain name to the Web server, this ping is closely related to the DNS server, and he is also going through DNS parsing to find a record of the domain name, So if the domain name parsing is not normal (99.99% is the state of the domain name is not normal, 0.01% is a DNS server problem), then you can not ping to the results.

This is the process of connecting your Web server from your browser input domain name to---

How to know if the domain name is parsed properly, ping the command. Can ping to its server IP, the description is normal parsing, it is specifically by which DNS server to resolve, you can also through the nslookup this command to query, so you can know which DNS server to do its parsing, and resolve to which IP. If you modify the DNS server for the domain name, this will cause you to ping directly or the results of the ping in both places are different, the DNS server will take 1-3 days to change. If you modify a record of a domain name or MX record, also need 1-24 hours to update, this situation will cause the two networks to ping the domain name, but ping out the record inconsistency, this is because the network update speed is different. In general, it is faster to change records.

Some issues that occur after you change the DNS server or change DNS records:

1> Change DNS server: Generally in the newly changed 24-72 hours, the use of Nslookup is not found, the WHOIS and other sites found on the results are not real-time, this period can only wait;

2> change DNS records: Fast One hours, slow one or two days will be effective and dissemination completed;

In your own local need to pay attention to the problem is: The local computer and local DNS server will have a cache, you see not necessarily 100% is the most real information, then you need to clear their own browser cache.

Step 2 : After you have connected to your Web server, the procedure for IIS requests

2.1) Some common errors in the operation of IIS and the site access process

Once the parsing is complete, your browser will go directly to your Web server, which is where you put your website files. To know that your site in our server corresponding to an IIS record, is to use this IIS record to find your website. Where is the IIS record? It in our server inside a program application pool, an IIS record can only be placed in a program application pool, when you buy a space, hosting system has created an IIS record for you, and it will be placed in which program application pool, half depending on you, half depends on the system. First, when you select your site type, you select the type of application pool for the program, so that the system can help you throw IIS records in. When this IIS record is found, it is triggered by an access request sent by your local computer through the browser, and IIS in the application pool will start to work if the settings for the application pool environment (site type) or the application pool are not working properly. Do not let the IIS record to the normal to contact your site's files. The following are IIS-level errors:

2.2) This is why sometimes when you visit your site, the following errors occur;

HTTP Error 500.23-internal Server error
An ASP setting have been detected that does not apply in Integrated managed pipeline mode

The hint is that your application does not run properly in the Integrated mode application pool, so you can switch your website to the Classic mode application pool to see if it works properly.

2.2.1) When such an error message appears:

"HTTP Error 503. The service is unavailable. "

This is due to the application pool exception shutdown, so the customer needs to contact hosting, then we will go to help him to see his website is the application pool is not working properly. Inside the AP, you can see the situation of each site.

2.2.2) The client's account expires and we no longer allow him to access the site, so requesting IIS is unsuccessful. This will jump to the other hosting preset pages.

2.2.3) When a website is wrong to choose the version of ASP. NET 2.0/3.5, but the actual site needs to asp.net4.0/4.5, you will get the following error;

Please note the Red font section;

Line: <compilation debug= "true" Batch= "false" targetframework= "4.0" >

When a local browser sends a request to IIS via the HTTP protocol, if the request is unsuccessful and an IIS-level error occurs, the system (the construction of the Protocol) will tell the browser which error interface to display, as above, based on the error code returned by IIS. The error is not related to the website file code.

2.3) You can define yourself in the configuration file of the website when the access error occurs, is not the most real error message, this is based on the success of the IIS request, has begun to read your Web site files. The error child node is set. If you need to take the customer to another page, you need to set it on this error child node.

About the two options in CP:

       1> hosting  account---iis manager --->asp .net  application manager --->detail error ,    this option is for asp.net  's website program , the customer can be here  turn on  or  turn off , then the impact is in the customer's website root folder will be corresponding to modify your Web config   File,   If this is set to on  then the corresponding  customer error mode =off in the Web config file  ,  is to go to the error page you set to temporarily close the function, and then show the most real error information about your site code level; if turn off  that's  web config. The   file displays the error page information you set yourself.   If you do not have a web config file yourself, then after you set it up here, the system will create the web config  file.   encountered code-level errors, we process when we call the client to go to the web config  file inside will this custom error  mode=off  can also be directly in this   asp.net application manager  here to set.   So here the config file says  custom error  and our control panel  custom error  is not a hierarchical concept.  

In summary, the Web Config file is in the customer's own web site settings, the IIS request will not work after the success, so this setting is not a level with the following 2), there is no conflict.

Note: The Web Web Control Panel does not have the option to let the customer go to the Web Config file to set it up.

2> Hosting Account--->iis Manager (Remote IIS Manager)--->custom errors, where IIS-level errors are set.

When an error is requested from IIS, the system returns an IIS error code so that the browser is directed to the appropriate error interface by IIS boot, which should follow the HTTP protocol. If the customer has made the error page Setup here, it is hoped that when the IIS request error occurs, it can be directed to the other custom interface instead of displaying the original IIS default orientation is the error page, which allows the browser to see the information you want him to see, commonly known as a friendly interface.

3> the IIS request (trigger) succeeds, the IIS record compiles the Web site script according to the site code of the root directory of the Web site, as well as some settings on the IIS record and the program application pool to display the appropriate site content. This phase is a combination of all content and settings in your website code and the application pool to pass information to the browser, telling the browser what to display. That's the process of opening a Web site file after the IIS request succeeds, and then the error that follows is the website file and the code level error:

After the IIS request succeeds, the problem that occurs is mostly 1) the client's website program does not run well in our application pool, 2) the customer's website code has the problem;

3.1>> If the administrator of this site has set the default page, this page is displayed, if the default page is not set, the browser does not know what interface should be displayed, there will be 403 access errors, the browser will be the Web server The information returned is translated into the page information that the user can read.

For example, when your site does not have to set the default homepage, the browser does not know which page to display, then the following error appears:

Error Summary
HTTP Error 403.14-forbidden
The WEB server is configured to the list the contents of this directory.
Detailed Error Information
Module Directorylistingmodule
Notification Executerequesthandler
Handler Staticfile
Error Code 0x00000000
Requested URL http://joysmarter2staff-001-site4.smarterasp.net:80/

Physical Path H:\root\home\joysmarter2staff-001\www\site4\config
Logon Method Anonymous
Logon User Anonymous
Please note that the Red Font section, the access to this URL is requested by the Config folder file, but because the Config folder does not have the default home page in the file, then the browser does not know what should be displayed, it will directly display 403 error. Then how to deal with this problem.

Has 3.1.1>>> uploaded the home file? Put the home file in the root folder of the Web site, and then go to his hosting account--->iis Manager--->default page, add you as the first page of the file name to the top row of the list, submit. We need to know which files may be the home page file, if nothing, then we have to look at the site folder which will be the home page, this can be changed by the access to the file to see which is the home page file.

3.2>> set the custom errors so the display is probably not the actual error message, first we must know whether the site has customized the error page, if there is a problem when visiting the site, the first thing is to go to the config file inside the custom The mode of the error is set to off so that the website displays the most realistic error messages, and then the next step of troubleshooting.