The URl is analysed
The paper
To understand by definition:
Uniform Resource Locator (URL), also called web page Address, is a standard Resource Address on the Internet. Every file on the Internet has a unique URL that contains information indicating where the file is and what the browser should do with it. It was originally invented by Tim Berners-Lee as the address for the World Wide Web. It has now been developed by the world wide web consortium as the Internet standard RFC1738. The beginning of a Uniform resource locator usually marks the network protocol used by a computer network.
Github.com/xihaoshangd…
This is a standard URL, generally speaking: URL = agreement + domain name | IP + port number + path + + anchor parameters, port number, generally USES the default port, port 80 provides the HTTP service, provide the HTTPS service port 443, 21 port provide FTP service.
DNS Domain name Resolution
Enter a standard URl to the browser, the agreement that in what way do we request, the domain name | IP specifications we request of the server status on the Internet, the port number that we requested service, the resources of the path that we request, the content of the parameters that we need to inform the server, the anchor will not be submitted.
An important step in this process is that domain names are meant for humans, but not for computers, so resolving a human-readable domain name into an IP address that a computer can recognize is called DNS resolution.
DNS resolution process:
- The client accesses the local hosts file and checks whether the corresponding domain name and IP address mapping exist in the file. If yes, the client sends a request to the IP address of the host. If no, the client searches for the local DNS server.
- The client sends a DNS query packet containing the domain name to the local DNS server.
- The local DNS server forwards the query packet to the root DNS server, and the root DNS server notices it
com|org|netThe IP address of the server with the corresponding suffix is returned to the local DNS server. - The local DNS server sends a query request to the DNS server with the corresponding suffix. The DNS server notices the suffix and responds with the IP address of the authoritative DNS server that is responsible for the domain name.
- Finally, the local DNS server sends the response packet containing the IP address to the client.
nslookup
Nslookup is used to query DNS records to check whether domain names are resolved properly and diagnose network faults.
- Direct query
Nslookup domain [dns-server] // If no DNS server is specified, the default DNS server is used.
- Other queries
nslookup -qt = type domain [dns-server]
| type: | meaning |
|---|---|
| A | –> Address record |
| AAAA | –> Address record |
| AFSDB Andrew | –> File system database server records |
| ATMA | ATM address record |
| CNAME | –> Alias record |
| HINHO | –> Hardware configuration records, including CPU and operating system information |
| ISDN | –> ISDN number of the domain name |
| MB | –> The server that stores the specified mailbox |
| MG | –> Mail group records |
| MINFO | –> Record information about mail groups and mailboxes |
| 先生 | –> Name changed mailbox record |
| MX | –> Mail server records |
| NS | –> Name server records |
| PTR | –> Reverse record |
| RP | –> Person in charge records |
| RT | –> Route penetration record |
| SRV | –>TCP server information |
| TXT | –> Text information corresponding to the domain name |
| X25 | –> X.25 address record of the domain name |
- Query more specific information
Nslookup -d [other parameters] domain [dns-server] nslookup -d [other parameters] domain [dns-server] nslookup -d [other parameters] domain [dns-server
The IP address
An IP address is a unified address format provided by the IP protocol. It allocates a logical address to each network and each host on the Internet to shield physical address differences.
In other words, an IP address is an ID card for every Internet user. But there are also extranets and intranets. An external IP address is an independent IP address, that is, a public IP address. However, multiple Intranet IP addresses may share one public IP address. NAT maps multiple Intranet IP addresses to one public IP address.
ping
ping [-t] [-a] [-n count] [-l length] [-f] [-i ttl] [-v tos] [-r count] [-s count] [-j computer-list] | [-k computer-list] [-w timeout] destination-list
| parameter | meaning |
|---|---|
| -t | Ping the specified computer until it is interrupted. |
| -a | Resolves the address to the computer name. |
| -n count | Send the number of ECHO packets specified by count. The default value is 4. |
| -l length | Sends ECHO packets containing the amount of data specified by length. The default is 32 bytes. The maximum is 65,527. |
| -f | Send “Do not fragment” flags in packets. Packets are not segmented by gateways on the route. |
| -i ttl | Set the TTL field to the value specified by TTL. |
| -v tos | Set the Service Type field to the value specified by TOS. |
| -r count | Record the routes of the outgoing and returned packets in the Record Route field. Count can specify a minimum of 1 and a maximum of 9 computers. |
| -s count | Specifies the timestamp of the specified hop point. |
| -j computer-list | Routing packets using a list of computers specified by computer-list. Continuous computers can be separated by intermediate gateways (routing sparse sources) the maximum number of IP addresses allowed is 9. |
| -k computer-list | Routing packets using a list of computers specified by computer-list. Continuous computers cannot be separated by intermediate gateways (routing strictly source) The maximum number of IP addresses allowed is 9. |
| -w timeout | Specifies the timeout interval in milliseconds. |
| destination-list | Specify the remote computer to ping. |
The domain name
Let’s look at the definition of a domain name:
Domain Name (English: Domain Name) is the Name of a computer or computer group on the Internet. It is used to identify the computer’s electronic location (sometimes also its geographical location) during data transmission. DNS (Domain Name System, sometimes referred to as Domain Name) is a core service of the Internet. As a distributed database that can map Domain names and IP addresses to each other, it can make people more convenient to access the Internet without remembering the NUMBER of IP addresses that can be read directly by the machine.
Take a look at the domain name administration:
The world’s top domain name authority is an organization called ICANN (Internet Corporation for Assigned Names and Numbers). Its headquarters are in California, USA. ICANN manages the operation of the world’s domain name system. One of its main tasks is to prescribe top level domains (TLD).
- The root of the domain name
Because ICANN manages all top-level domains, it is the highest level of domain name nodes, known as root domains. In some cases, www.example.com is written as www.example.com., with an extra dot at the end. This dot is the root domain. In theory, all domain name queries must start with the root domain, because only the root domain can tell you which server manages a top-level domain. Indeed, ICANN maintains a list of top-level domains and their corresponding hosts.
- Top-level domain names
A top-level domain name (TLD) is the highest level domain name. In short, it is the last part of the website. For example, the top-level domain of the web site www.example.com is.com.
- Subordinate domain name