DNS domain name resolution service

Catalog

One 、BIND Domain name service foundation

1、DNS Concept

2、DNS Parsing type

3、DNS Protocol and port number used

4、 Domain name Architecture

5、 Two ways to query

① recursive query

② Iterative query

Two 、BIND Installation and configuration files for

summary ：

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One 、BIND Domain name service foundation （DNS The name of the installation of is BIND, The service name is named, The agreement is called DNS ）

1、DNS Concept

Concept ：DNS DNS is a core service of the Internet , It can be used to IP A distributed database with address mapping , Can make people more convenient access to the Internet , Instead of remembering complex IP Address . It is for the convenience of users' memory and use .

All over the world 13 platform （ this 13 The name of the root DNS server is "A" to "w"),1 Primary root servers in the United States . rest 12 Secondary root servers , among 9 One in America , The European 2 individual , Located in the UK and Sweden , Asia 1 In Japan .

2、DNS Parsing type

Forward analysis ： Also called DNS The host A Record ： Domain name resolves to ——》IP Address

Reverse DNS ： Also called DNS The host P Record ：IP Address resolution into ——》 domain name

3、DNS Protocol and port number used

DNS The default port is 53.DNS Ports are divided into TCP and UDP.

①TCP It is used for area transmission , Mostly used for master-slave synchronization

②UDP Is used to do DNS Analytic

4、 Domain name Architecture

Root region ： At the top of the tree , use "." Express

Top-level domain ： It generally represents a type of organization or country or region （ Such as .net( Network providers )、.com( Industrial and commercial enterprises )、.org（ Group organizations ）、.edu（ The structure of education ）、.gov( Government sector )、.cn（ Chinese national domain name ））

The secondary domain ： Used to identify a specific organization in the top-level domain , The secondary domain names under the national top-level domain are under the unified management of national departments

Subdomain ： All levels of domains created under the secondary domain are collectively referred to as subdomains , Organizations or users are free to apply for their own domain names

host ： The host is at the bottom of the domain name space , It's a concrete computer

Root domain name (.)

First level domain name :.cn( China ). us( Rice country ) .tw( Taiwan ) .kr（ South Korea ).jp( Japan ).hk（ Hong Kong ).uk ( The British )

Two level domain name :.com.cn ( Chinese business organizations ) .edu.cn ( educational services ) .org.cn ( uncommercially ) .net.cn( Chinese operators )

Three level domain name : sina.com.cn nb.com.cn haixi.com.cn ...... . ..

Organizational domain :.com .org .net .cc

National domain : .cn( China ) .tw（ Taiwan ) .hk( Hong Kong ) .iq .ir .jp ( Japan ) Reverse domain

114.114.114.114      It is owned by three major operators DNS

8.8.8.8                     yes Google Provided by the company DNS

5、 Two ways to query

① recursive query

Recursive query is a kind of DNS The query mode of the server , In this mode DNS The server received a client request , You must reply to the client with an accurate query result . If DNS The server does not store queries locally DNS Information , Then the server will ask other servers , And submit the returned query results to the client . After the client sends the request, it only needs to wait for the result , The middle specific process is handed over to the server to realize

client ——》 Local DNS The server ： This part belongs to recursive query

② Iterative query

DNS Another query method of the server is iterative query , When the client sends a query request ,DNS The server does not reply directly to the query results , Instead, tell the client another DNS Server address , The client will go to this DNS The server submits the request , Loop back and forth until the result of the query is returned . The client's request needs to be queried one by one to get the result , When the server has no results, it will only provide you with the address of other servers , Instead of asking for information for you , This is the opposite of recursion .

Local DNS Server side ——》 Extranet ： This part belongs to iterative query

Two 、BIND Installation and configuration files for

1、 install    yum -y install bind

 2、 Global profile （ Global effective configuration ）  vim /etc/named.conf

3、 Set the regional profile    vim /etc/named.rfc1912.zones

  Access content , Only add the domain name and regional data configuration file name

4、 Configure area data file .

cd /var/named/                                                        Get into /var/named/ Under the table of contents

cp -p named.localhost zhangsan.com.zone            Copy the template area data profile and rename

vim /var/named/zhangsan.com.zone                      Modify the configuration file contents

5、 modify /etc/resolv.conf  The server address of , Point to the local DNS service

 6、 test

① analysis www.zhangsan.com

② analysis ftp.zhangsan.com

 

③ analysis mail.zhangsan.com

④ analysis ： Any one that is not within the scope of definition

summary ：

To study the DNS The role of , Its working principle and DNS How to query when working . Experimental configuration DNS service .