Simple DNS Protocol Configuration

DNS (Domain Name System) is a distributed database that maps domain names and IP addresses on the Internet, allowing users to access the Internet more conveniently, instead of remembering the number of IP address strings that can be directly read by machines. The process of obtaining the IP address corresponding to the host name through the host name is called domain name resolution (or host name resolution ). The DNS protocol runs on the UDP protocol and uses the port number 53.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/44/85/wKiom1Ph3gezYgxWAAAL4EQBpms838.png "Title =" DNS principle. PNG "alt =" wkiom1ph3gezygxwaaal4eqbpms838.png "/>

As a hierarchical and distributed database, the domain name system contains various types of data, including host names and domain names. The name in the DNS database forms a layered tree structure called the domain namespace. The fully qualified domain name (FQDN) uniquely identifies the host location in the DNS Hierarchy Tree and separates the names of the hosts referenced from the root using the specified path midpoint.

How DNS domain name space is organized

Type	Description	Example
Root Domain	When using a DNS domain name, it is required that the domain name is located at the root or higher level by the end (.).	The name at the end of a single or period.
Top-level domain	Indicates the name type used by a country or region for organization.	. Com
Second-level domain	Registration name used by an individual or an ancestor on the Internet	QQ.com 163.com
Subdomain	A domain name derived from a registered second-level domain name	Aq.qq.com
Alias	The leftmost tag of the DNS domain name identifies a specific host on the network

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/44/97/wKioL1Ph_c2CswbBAAFhcN3wXA4351.jpg "Title =" 201307141950351941.jpg" alt = "wkiol1ph_c2cswbbaafhcn3wxa4351.jpg"/>

Resource Record: RR (Resource Record)

Type concept: attributes used for parsing this record

SOA: the initial Authorization Record. Only one region file can exist;

NS: Name Server

MX: email exchange. The MX record has a priority attribute (0-99 );

A: FQDN --> IP address, dedicated to forward resolution Library

PTR: IP --> FQDN, used for reverse resolution Library

Aaaa: FQDN --> IPv6, dedicated to forward resolution Library

Cname: official name

Resource Record type:

SOA: Name region name, which can be abbreviated as @ value: FQDN of the primary DNS server, or the region name of the current region;

Format

@ In SOA ns.magedu.com. admin.magedu.com .(

Serial number; the version number of the Resolution database, for example, 2014080401

Refresh time; interval of periodic Synchronization

Retry time; Retry Interval

Expire time; expiration time

Negative answer TTL; Unified cache duration of negative answers

NS name: Region name value: FQDN of the DNS server

Format

@ In NS ns.magedu.com.

If there are multiple NS servers, each of them must have corresponding NS records;

For forward parsing files, each ns fqdn should have a record;

MX name region name value: FQDN of the email server

Format

@ In MX 10 mail.magedu.com.

If there are multiple MX servers, each one must have a corresponding MX record; however, each MX record also has a priority attribute.

For forward parsing files, each ns fqdn should have a record;

A name FQDN value: IP

Cname name FQDN value: FQDN

PTR: pointer

Name: reverse Host IP address and suffix in-addr.arpa, such as 172.16.100.7/16, network address is 172.16, host address is 100.7, its name is 7.100.in-ADDR. ARPA.

Value: FQDN

DNS query

DNS resolution mainly involves recursive queries. When the corresponding domain name and IP address cannot be found in the cache of a DNS server, the system automatically jumps to the next step and searches through the next DNS server.

Host-local NDS server-DNS root server

Bind of DNS

Service Script:/etc/rc. d/init. d/named

Main configuration file:/etc/named. conf,/etc/named. rfc1912.zones

Region resolution library file:/var/named/zone_name.zone

1. After installing the BIND Program

Modify the main configuration file:

Define Region

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/44/93/wKiom1Ph9bbA9Y7YAABKxOKTkQc998.png "style =" float: none; "Title =" named. conf. PNG "alt =" wkiom1ph9bba9y7yaabkxoktkqc998.png "/>

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/44/93/wKioL1Ph9s_Cu1GFAAAe4cwUA_k233.png "style =" float: none; "Title =" named. RFC. PNG "alt =" wkiol1ph9s_cu1gfaaae4cwua_k233.png "/>

3. Provide a resolution database for each region

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/44/A8/wKioL1PiJROi5wGlAAAnPCzvOC4720.png "Title =" fengshi 111111111111.png" alt = "wkiol1pijroi5wglaaanpczvoc4720.png"/>

After

# Service named start

Available for testing

1. Host-T rrtype name [server]

2. Dig-T type name @ Server

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/44/A8/wKioL1PiJWfzA28CAAAU74r09Jw479.png "Title =" qqqqqqqqqqqqqqqqqqqqqqqqqqqq. PNG "alt =" wkiol1pijwfza28caaau74r09425479.png "/>

Master/Slave configurations of DNS servers

1. modify the configuration file on the master server as follows:

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/44/A7/wKiom1PiIwLwQ55wAAAhu2nkf8A116.png "Title =" Capture. PNG "alt =" wkiom1piiwlwq55waaahu2nkf8a116.png "/>

2. Create test. Zone

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/44/A8/wKiom1PiI0uhhKFaAAAmWBEwbm0977.png "Title =" test. Zone. PNG "alt =" wkiom1pii0uhhkfaaaamwbewbm0977.png "/>

3. Set files on the slave server

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/44/A8/wKioL1PiJK_w91OAAAAc8tffkcY518.png "Title =" aaaaaaaaaa. PNG "alt =" wkiol1pijk_w91oaaaac8tffkcy518.png "/>

4. Results

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/44/A8/wKiom1PiI8WThdEiAAAFE76xEAI179.png "Title =" jieguo. PNG "alt =" wkiom1pii8wthdeiaaafe76xeai179.png "/>