Shulou(Shulou.com)06/03 Report--

DNS domain name system

IP address is used to identify the uniqueness of one's identity in computing on the Internet. IP is hard to remember. So there is the DNS domain name system.

DNS: domain name system domain name system. The corresponding (mapping map) relationship between domain name and IP address is recorded in DNS system.

The corresponding relationship between other people's names and phone numbers is recorded in the mobile phone book.

Forward resolution (commonly used): implements the resolution of domain names to IP addresses. Domain name-> IP address.

Reverse resolution (not commonly used): implements the resolution of IP addresses to domain names. IP address-- > domain name.

Forward domain name resolution process: what is the IP address that requests "www.baidu.com" to the local DNS server-- > root DNS server-- > first-level domain name server-- > second-level domain name server?

Identity of the DNS server:

Master DNS server (master master): an authoritative service used in the DNS system to record the correspondence between domain names and IP addresses (resource configuration files). It can be understood as the general manager of the company.

Secondary DNS server (slave standby): equivalent to the vice president of the company. The resource profile on the secondary DNS server comes from the primary DNS server. Automatically downloads the resource profile from the primary DNS server, or periodically synchronizes the resource profile data with the primary DNS server. The secondary DNS server can help the primary DNS server to share the pressure of domain name resolution.

Cache DNS server (cache cache): used to cache data for domain name resolution. It can be used as a DNS parsing accelerator.

Naming rules for domain names:

Example www.baidu.com

Domain name format: hostname. Second-level domain name. First-level domain name [. The root domain name adopts a hierarchical structure.

The name of the foreigner: first name. Last name

Com 1.1.1.1

Net 2.2.2.2

Root domain: use. The dot means. The root domain is the top level of the domain name system. There are 13 root domain servers worldwide. Most root domain servers are in the United States.

First-level domain name: used to identify the category of the organization. As follows:

Com enterprise, company net network organization org non-profit organization cn China hk Hong Kong

Gov government agency edu educational institution tw Taiwan

Secondary domain name: used to identify the name of the organization. Usually, a company or individual applies to the domain name system administration for a name to identify. Common secondary domain names of Internet companies are as follows:

Ali: ali Taobao taobao 58.com 58 Tencent qq, tencent NetEase 163Sina sina

Third-level domain name (or host name): group companies are usually used to identify companies in different regions. For example, 58.com 's companies are: wh.58.com, hz.58.com, bj.58.com.

Forward resolution process of DNS domain name: www.baidu.com

Www.baidu.com 180.97.33.107

1. The client client sends a parsing request to the local DNS server: "do you know the IP address of www.baidu.com"? The server queries its own DNS database for regional and resource records of www.baidu.com.

2. If there is a record on the local DNS server, tell the client the IP address of the www.baidu.com directly. Otherwise, the local DNS server goes back to ask the "root" DNS server.

3. The root DNS server tells the local DNS server .com DNS server IP address.

4. The local DNS server sends a request to the .com server: "do you know the IP address of www.baidu.com"?

5. The DNS server of .com tells the local DNS server baidu.com the DNS server IP address.

6. The local DNS server sends a request to the baidu.com server: "do you know the IP address of www.baidu.com"?

7. Baidu.com 's DNS server tells the local DNS server www.baidu.com 's server IP address.

8. The local DNS server tells the Client client that the IP address of "www.baidu.com" is 180.97.33.107.

9. The Client client sends a request to the WEB server of www.baidu.com at IP address 180.97.33.107, "Please give me a home page file of the website, such as index.html"

10. The WEB server 180.97.33.107 transmits the home page file of the website to the Client client using http protocol.

File path: / etc/sysconfig/network-scripts/ifcfg-ens33

Information recorded by the DNS server in the root domain:

Hostnam

IP address

Com

1.1.1.1

Cn

2.2.2.2

Net

3.3.3.3

The information recorded by com's DNS server:

Hostnam

IP address

Baidu.com

1.1.1.2

Sina.cn

2.2.2.5

163.net

3.3.3.5

The information recorded by baidu.com 's DNS server:

Hostnam

IP address

Www.baidu.com

1.1.1.3

Pan.baidu.com

1.1.1.4

Map.baidu.com

1.1.1.5

Deployment of the DNS server:

Server software: bind service name: named

Client software: bind-utils

Network topology configured by the DNS service:

Main DNS server: 192.168.11.11

Secondary DNS server: 192.168.11.12

DNS client: 192.168.11.1

Server deployment ideas:

1. Check whether the software is installed: rpm-Q bind bind-utils

two。 Installation software: yum install-y bind bind-utils

3. Startup service, allowing boot to start automatically: systemctl restart named & & systemctl enable named

4. | check the service status, and check the network process port: systemctl status named or lsof-ipur.53 or netstat-atunlp | grep: 53 |

Commands for 5.DNS server profile syntax detection:

Named-checkconf

Named-checkzone localhost / var/named/named.localhost

Detect / etc/named.conf main profile syntax

Detect the syntax of the localhost zone configuration file

6. Check the configuration file: rpm-qc bind

/ etc/logrotate.d/named

/ etc/named.conf

/ etc/named.iscdlv.key

/ etc/named.rfc1912.zones

/ etc/named.root.key

/ etc/rndc.conf

/ etc/rndc.key

/ etc/sysconfig/named

/ var/named/named.ca

/ var/named/named.empty

/ var/named/named.localhost

/ var/named/named.loopback

Log roll policy file for DNS

Main configuration file for DNS

DNS locale profile (forward parsing, reverse parsing locale)

7. Modify the configuration file / etc/named.conf for DNS.

Cd / etc

Ls named*

Cp-v named.conf named.conf.bak

Vim named.conf

Modify the following

Options {

Listen-on port 53 {any;}

Listen-on-v6 port 53 {:: 1;}

Directory "/ var/named"

Dump-file "/ var/named/data/cache_dump.db"

Statistics-file "/ var/named/data/named_stats.txt"

Memstatistics-file "/ var/named/data/named_mem_stats.txt"

Recursing-file "/ var/named/data/named.recursing"

Secroots-file "/ var/named/data/named.secroots"

Allow-query {any;}

Recursion yes

Dnssec-enable yes

Dnssec-validation yes

/ * Path to ISC DLV key * /

Bindkeys-file "/ etc/named.iscdlv.key"

Managed-keys-directory "/ var/named/dynamic"

Pid-file "/ run/named/named.pid"

Session-keyfile "/ run/named/session.key"

}

Logging {

Channel default_debug {

File "data/named.run"

Severity dynamic

}

}

Zone "." IN {

Type hint

File "named.ca"; file path is / var/named/named.ca

}

Include "/ etc/named.rfc1912.zones"

Include "/ etc/named.root.key"

Option settin

Listening port is 53, listening IPv4 is 127.0.0.1, and it can also be any IP of any.

Working directory of the DNS service

Cache file

Status information file

Internal state information file

Query is allowed. Localhost means that only the local machine is allowed to check it. If you want any host in the network to query, use any. (whitelist)

Allow recursive queries

Enable DNS security featur

PID file for the DNS service

Root domain settings

Type is hint root domain

Resource record file name for hostname and IP address mapping

Specifies the included profile, where named.rfc1912.zones is the zone profile

8. Configure zone information for forward resolution.

Cd / etc

Cp-v named.rfc1912.zones {, .bak}

Vim named.rfc1912.zones

Zone "localhost.localdomain" IN {

Type master

File "named.localhost"

Allow-update {none;}

}

Configure the localhost.localdomain name area

Type is master main area

The resource record file is named named.localhost, and the full path is / var/named/named.localhost

Updates are allowed, but none is not allowed

Exercise: create a forward resolution zone named qf.com in the named.rfc1912.zones zone configuration file.

Step 1, create the configuration information for the forward parsing area of qf.com.

Vim / etc/named.rfc1912.zones

Add the following to the last line of the file

Zone "qf.com" IN {

Type master

File "qf.com.zx"

Allow-update {none;}

Allow-transfer {192.168.11.15;}

}

Configure the localhost.localdomain name area

Type is master main area

The resource record file is named qf.com.zx, and the full path is / var/named/qf.com.zx

Updates are allowed, but none is not allowed

Allow the transfer of resource data from the qf.com area to the 192.168.11.15 host

Step 2, create the resource record (mapping relationship between domain name and IP address) file qf.com.zx for the qf.com forward resolution area.

Cd / var/named

Ls

Cp-av named.localhost qf.com.zx

Vim qf.com.zx

The contents of the modified file are as follows

$TTL 1D

@ IN SOA dns.qf.com. 12700696.qq.com. (

0; serial

1D; refresh

1H; retry

1W; expire

3H); minimum

NS @

A 127.0.0.1

NS dns.qf.com.

Dns A 192.168.11.11

AAAA:: 1

Www A 1.1.1.1

Ftp A 1.1.1.2

Mail A 1.1.1.3

Web CNAME www.qf.com.

The life cycle value of cached data is 1 day.

SOA record, specifying authoritative DNS server name and administrator mailbox

The version number of the modified file, usually written with the number of year, month and day, such as 20190213001

Refresh time is 1D (that is, 1 day)

The retry time is 1H (i.e. 1 hour)

Expiration time is 1W (that is, 1 week)

The default cache time is 3H (that is, 3 hours)

NS record, or name server record

NS record, specifying the DNS server name

A record, which specifies the IP address corresponding to the domain name

A record, the IP address corresponding to the specified www hostname is 1.1.1.1

A record, address record

A record

CNAME alias record, which defines the alias as web.qf.com for the www.qf.com domain name

Note: @ in the configuration file is a variable, and the value of the @ variable is the "domain name" in the line of zone code in / var/named.rfc1912.zones.

Step 3, check the syntax of the two configuration files of DNS, restart the named service, and do the internal test of DNS (local test).

Named-checkconf

Named-checkzone www.qf.com / var/named/qf.com.zx

Systemctl restart named

Nslookup

Server

Server 192.168.11.11

Www.qf.com

Ftp.qf.com

Web.qf.com

Detect / etc/named.conf syntax (optional)

Detect the syntax of the qf.com.zx zone profile (optional)

Restart the named service

Run the DNS client software nslookup

View the current default DNS server IP information

Temporarily set the DNS resolution server IP to 192.168.11.11

Query the IP address of the www.qf.com domain name

Same as above

Same as above

Exercise: refer to the creation method of the qf.com forward resolution zone, create a domain name named baidu.com on the 192.168.11.11 DNS server, and create a resource record file baidu.com.zone for the region of the domain name. Finally, the forward parsing test is done.

Vim / etc/named.rfc1912.conf

Zone "baidu.com" IN {

Type master

File "baidu.com.zone"

Allow-update {none;}

}

Cd / var/named

Cp-av qf.com.zx baidu.com.zone

The vim baidu.com.zone content is as follows

$TTL 1D

@ IN SOA dns.baidu.com. 12700696.qq.com. (

0; serial

1D; refresh

1H; retry

1W; expire

3H); minimum

NS @

A 127.0.0.1

NS dns.baidu.com.

Dns A 192.168.11.11

AAAA:: 1

Www A 2.2.2.1

Ftp A 2.2.2.2

Mail A 2.2.2.3

Web CNAME www.baidu.com.

Step 3, check the syntax of the two configuration files of DNS, restart the named service, and do the internal test of DNS (local test).

Named-checkconf

Named-checkzone www.baidu.com / var/named/qf.baidu.zx

Systemctl restart named

Nslookup

Server

Server 192.168.11.11

Www.baidu.com

Ftp. Baidu.com

Web.baidu.com

Detect / etc/named.conf syntax (optional)

Detect the syntax of the qf.com.zx zone profile (optional)

Restart the named service

Run the DNS client software nslookup. Win7/10 also uses this command

View the current default DNS server IP information

Temporarily set the DNS resolution server IP to 192.168.11.11

Query the IP address of the www.baidu.com domain name

Same as above

Same as above

9. Configure zone information for reverse resolution.

Exercise: create a reverse resolution zone named 192.168.5.0 in the named.rfc1912.zones zone configuration file.

Step 1, create the configuration information for the 192.168.5.0 reverse parsing area.

Vim / etc/named.rfc1912.zones

Add the following to the last line of the file

Zone "5.168.192.in-addr.arpa" IN {

Type master

File "192.168.5.fx"

Allow-update {none;}

}

Configure 5.168.192.in-addr.arpa reverse resolution area

Type is master main area

The resource record file is named 192.168.5.fx, and the full path is / var/named/192.168.5.fx

Updates are allowed, but none is not allowed

Step 2, create the resource record (mapping relationship between domain name and IP address) file 192.168.5.fx for the 192.168.5.0 reverse resolution area.

Cd / var/named

Ls

Cp-av named.loopback 192.168.5.fx

Vim 192.168.5.fx

The contents of the modified file are as follows

$TTL 1D

@ IN SOA dns.qf.com. 12700696.qq.com. (

0; serial

1D; refresh

1H; retry

1W; expire

3H); minimum

NS @

A 127.0.0.1

AAAA:: 1

PTR localhost.

[u1] NS dns.qf.com.

Dns A 192.168.11.11

2 PTR www.qf.com.

3 PTR ftp.qf.com.

4 PTR mail.qf.com.

The life cycle value of cached data is 1 day.

SOA record, specifying authoritative DNS server name and administrator mailbox

The version number of the modified file, usually written with the number of year, month and day, such as 20190213001

Refresh time is 1D (that is, 1 day)

The retry time is 1H (i.e. 1 hour)

Expiration time is 1W (that is, 1 week)

The default cache time is 3H (that is, 3 hours)

NS record, or name server record

A record, which specifies the IP address corresponding to the domain name

PTR record, which specifies the hostname corresponding to the IP address

D Note: @ in the configuration file is a variable, and the value of the @ variable is the "domain name" in the line of zone code in / var/named.rfc1912.zones.

Step 3, check the syntax of the two configuration files of DNS, restart the named service, and do the internal test of DNS (local test).

Named-checkconf

Named-checkzone 192.168.5.2 / var/named/192.168.5.fx

Systemctl restart named

Nslookup

Server

Server 192.168.11.11

192.168.5.2

192.168.5.3

192.168.5.4

Exit

Detect / etc/named.conf syntax (optional)

Detect the syntax of the 192.168.5.fx zone profile (optional)

Restart the named service

Run the DNS client software nslookup

View the current default DNS server IP information

Temporarily set the DNS resolution server IP to 192.168.11.11

Query the domain name corresponding to the IP address of 192.168.5.2

Same as above

Same as above

Exit the nslookup client software

Technical points: secondary DNS server

Secondary DNS server: 192.168.11.12

Requirements: build the main DNS server according to the above experimental content, create the forward domain name resolution zone and reverse domain name resolution zone specified above, and test them. Then install the bind and bind-utils software on 192.168.11.12, configure the secondary DNS server, and create the auxiliary DNS parsing function of the qf.com zone.

The following is the operation on the host 192.168.11.12

Step 1, install the software.

Rpm-Q bind bind-utils

Yum install-y bind bind-utils

Systemctl restart named & & systemctl enable named

Rpm-qc bind

Step 2, back up the specified configuration file.

Cd / etc

Ls named*

Cp-v named.conf {, .bak}

Cp-v named.rfc1912.zones {, .bak}

Step 3, modify the / etc/named.conf main configuration file, changing all 127.0.0.1 and localhost in the file to any.

Vim / etc/named.conf modifies the content in {} of the following two lines to any

Listen-on port 53 {any;}

Allow-query {any;}

Detect named.conf syntax: named-checkconf

Step 4, create a secondary DNS parsing parameter for qf.com in the zone configuration file / etc/named.rfc1912.zones.

Vim / etc/named.rfc1912.zones

Zone "qf.com" IN {

Type slave

File "slaves/qf.com.zx"

Allow-update {none;}

Masters {192.168.11.11;}

}

Declare the IP address of the primary DNS server

Step 5, check to see if there are qf.com.zx files in the / var/named and / var/named/slaves directories, restart the named service, and then see if there are qf.com.zx resource record files.

Ls / var/named/ var/named/slaves

Systemctl restart named

Ls / var/named/ var/named/slaves found the qf.com.zx file in the / var/named/slaves directory, which was downloaded from the main DNS server 192.168.11.11.

Comprehensive activity for primary DNS and secondary DNS server:

Preparation: make sure that bind software is installed on both the primary DNS and the secondary DNS server, and the named service is started, and the 127.0.0.1 and localhost in the / etc/named.conf main configuration file are changed to any. Restart the named service and do the following.

Primary DNS server: (operating on 192.168.11.11 host)

Create a forward parsing area of sina.com whose resource record configuration file is named / var/named/sina.com.zone, and the contents of the resource record file refer to the contents of qf.com.zx.

Vim / etc/named.rfc1912.zones

Zone "sina.com" IN {

Type master

File "sina.com.zone"

Allow-update {none;}

Allow-transfer {192.168.11.12;}

}

Cd / var/named

Cp-av named.localhost sina.com.zone

Vim sina.com.zone

Add the following at the end of the file

Www A 1.2.3.4

Ftp A 1.2.3.5

Mail A 1.2.3.6

A 1.2.3.7

* A 1.2.3.8

Web CNAME www.sina.com.

Pan-domain name resolution record. * asterisk is a wildcard that matches any 0 or more characters.

Systemctl restart named

Host www.sina.com 127.0.0.1

Dig web.sina.com @ 127.0.0.1

Secondary DNS server: (operating on 192.168.11.12 host)

Create a forward parsing region of sina.com with the type slave and its resource record configuration file named slaves/sina.com.slave. Specify that his primary DNS server IP address is 192.168.11.11. Refer to the secondary DNS server configuration steps of qf.com above.

Vim / etc/named.rfc1912.zones

Zone "sina.com" IN {

Type slave

File "slaves/sina.com.slave"

Allow-update {none;}

Masters {192.168.11.11;}

}

Ls / var/named/slaves

Systemctl restart named

Ls / var/named/slaves

Host www.sina.com 192.168.11.12

Dig web.sina.com @ 192.168.11.12

02-14AM

Exercise: refer to the forward parsing area of qf.com to create a positive parsing area of qq.com on the 192.168.11.11 DNS server, the resource record configuration file is / var/named/qq.com.zone, and the content of the resource record configuration file can be flexibly defined.

Rpm-Q bind bind-utils

Yum install-y bind bind-utils

Systemctl restart named & & systemctl enable named

Lsof-iatunlp 53 or netstat-atunlp | grep: 53

Cd / etc

Ls named*

Cp-v named.conf named.conf.bak

Cp-v named.rfc1912.zones named.rfc1912.zones.bak

Vim / etc/named.conf modifies all 127.0.0.1 and localhost in the file to any

Named-checkconf detects named.conf syntax

Vim / etc/named.rfc1912.zones adds the following at the end of the file

Zone "qq.com" IN {

Type master

File "qq.com.zone"

Allow-update {none;}

Allow-transfer {192.168.11.12;}

}

Cd / var/named

Ls

Cp-av named.localhost qq.com.zone

Vim qq.com.zone adds the following at the end of the file

Www A 1.1.1.1

Ftp A 1.1.1.2

Mail A 1.1.1.3

Web CNAME www.qq.com.

Syntax checking: named-checkzone www.qq.com / var/named/qq.com.zone

Restart the service: systemctl restart named

Local parsing test for DNS (internal test): nslookup www.qq.com 127.1

Host web.qq.com 127.1

Dig web.qq.com @ 127.1

The view function of DNS:

DNS view: through the view function, you can resolve different IP addresses from intranet and extranet. That is to say, when resolving the same domain name, the clients of different network segments will query the IP addresses of different results.

Warning: delete or comment out the configuration information of the root domain in / etc/named.conf and comment out the code such as named.rfc1912.zones and root.key on the DNS server that uses the DNS view function. Otherwise, an error will occur.

DNS view code: / etc/named.conf

Acl dianxin {defines the access control list name as dianxin Telecom

192.168.10.0amp 24; specify the network address and subnet mask, 24 is the subnet mask of 255.255.255.0

}

View "dianxin" {defines the view name as dianxin Telecom

Match-clients {dianxin;}; the network segment of the matching client is dianxin (that is, the name defined by acl)

Recursion yes; enables recursive query

Zone "test.com" IN {Register test.com matching configuration

Type master; type is master primary DNS server

File "dianxin.test.com.zone"; parsing resource profile for the zone

}

}

Exercise: temporarily add 2 IP addresses (192.168.100.7 [Mobile], 192.168.110.7 [Unicom]) to the ens33 network card of this host. Create a view of dianxin, define the test.com area in the view, and create a parsing resource record file with a hostname and IP address, but the IP must be in the network segment 192.168.10.0. Do an analytical test.

Ifconfig ens33:1 192.168.100.7 up

Ifconfig ens33:2 192.168.110.7 up

Vim / etc/named.conf modifies the following (the yellow background is something that must be commented out)

# zone "." IN {

# type hint

# file "named.ca"

#}

# include "/ etc/named.rfc1912.zones"

# include "/ etc/named.root.key"

# the following is the new content to be added

Acl dianxin {

192.168.10.0/24

}

View "dianxin" {

Match-clients {dianxin;}

Recursion yes

Zone "test.com" IN {

Type master

File "dianxin.test.com.zone"

}

}

Create the parsing configuration file dianxin.test.com.zone:

Cd / var/named

Cp-pv named.localhost dianxin.test.com.zone

The vim dianxin.test.com.zone content is as follows

$TTL 1D

@ IN SOA dns1.test.com. 12700696.qq.com (

0; serial

1D; refresh

1H; retry

1W; expire

3H); minimum

NS dns1.test.com.

Dns1 A 192.168.10.7

AAAA:: 1

Www A 192.168.10.11

Ftp A 192.168.10.12

Mail A 192.168.10.13

Local resolution test:

Systemctl restart named

Nslookup dns1.test.com 192.168.10.7

-

DNS subdomain authorization:

The meaning of child domain authorization is to find out the mapping relationship between domain name and IP address in child domain DNS server on the parent domain DNS server.

Subdomains: everything except the root domain is called a subdomain

Why use subdomains?

Reduces the burden on the parent domain and is not affected by dns service providers

Subdomains are generally used within the company.

The parent domain only needs to resolve its own child domain.

The subdomain completes the resolution of all hosts in the subdomain.

Child domain authorization: it refers to registering the domain name of the child domain on the parent domain server and the IP address of the server where the domain name information is located.

The code for the authorization of the subdomain name (the code added in the resource resolution profile of the zone):

Subdomain name NS hostname. Subdomain name.

Hostname. Subdomain name. An IP address

NS dns1.qf.com

Dns1 A 192.168.11.11

Wh NS 58.com.

Bj NS 58.com.

Hz NS 58.com.

Wh.58.com. A 192.168.11.12

Bj.58.com. A 192.168.11.13

First-level domain name service 192.168.11.11 (parent domain): region name com IP:192.168.11.11

Second-level domain name server (subdomain): zone name sohu.com IP:192.168.11.12

Implementation reference:

Step 1, configure the secondary domain name server sohu.com (completed on the host 192.168.11.12)

Setenforce 0

Systemctl stop firewalld

Vim / etc/named.conf adds the following

Zone "sohu.com" IN {

Type master

File "sohu.com.zone"

Allow-update {none;}

Allow-transfer {none;}

}

--

Cd / var/named

Cp-pv named.localhost sohu.com.zone

The vim sohu.com.zone content is as follows

$TTL 1D

@ IN SOA dns1.sohu.com. 12700696.qq.com. (0 1D 1H 1W 3H)

NS dns1.sohu.com.

Dns1 A 192.168.11.11

Www A 192.168.13.11

Ftp A 192.168.13.12

Mail A 192.168.13.13

--

Systemctl restart named

Nslookup dns1.sohu.com 192.168.11.12

-

Step 2, configure the first-level domain name server com. (done on the host of 192.168.11.11)

Setenforce 0

Systemctl stop firewalld

Vim / etc/named.conf adds the following

Zone "com" IN {

Type master

File "com.zone"

Allow-update {none;}

Allow-transfer {none;}

}

-

Cd / var/named

Cp-pv named.localhost com.zone

The vim com.zone content is as follows

$TTL 1D

@ IN SOA dns1.com. 12700696.qq.com. (0 1D 1H 1W 3H)

NS dns1.com.

Sohu.com. NS dns1.sohu.com. # declare that the subdomain name sohu.com is saved in the server dns1.sohu.com

Dns1.com. A 192.168.11.11 # IP address of the first-tier domain name server com

Dns1.sohu.com. A 192.168.11.12 # IP address of the dns1.sohu.com secondary domain name server

Note: NS record: specify the domain name and the location where the domain name is saved (that is, on which server)

Restart the service: systemctl restart named

Parsing test at 192.168.11.11: nslookup dns1.com 192.168.11.11

Parsing test at 192.168.11.11: nslookup ftp.sohu.com 192.168.11. [U2] 11

The meaning of child domain authorization is to find out the mapping relationship between domain name and IP address in child domain DNS server on the parent domain DNS server.

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Not on this trip.

The IP of the parent domain server. Look up the child domain server in the parent domain server (write the ip of the parent server). The information found is the domain name and the corresponding IP written in the resource configuration file of the child domain server.

The IP checked is the IP of the parent domain server, and the information of the child domain server is displayed.

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