Shulou(Shulou.com)06/02 Report--

Deploy DNS services and manage DNS

I. Overview of DNS

1. Early use of HOSTS files to resolve domain names

Duplicate host names and difficult host maintenance

2. Disadvantages of hosts: the names are easy to repeat, and the efficiency of large file parsing is reduced.

Single point of management host is prone to failure

3. HOST file location: Hosts file% SystemRoot%\ system32\ drivers\ etc

4. DNS (Domain Name System) Domain name Resolution system

5. Function: domain name is resolved to IP address

IP address is resolved to domain name

Now: the DNS service resolves domain names

Hierarchy: divide DNS into four-tier structure

Distributed: each tier structure is managed by different DNS servers

2. DNS spatial structure (hierarchy)

1. Root domain: "."

2. Top-level domain: country region and organizational domain, as shown in the following table

Top-level domain name description

Gov government departments

Com Business Division

Edu Education Department

Org civil society organization

Net network service organization

Mil military department

3. Secondary domain (sohu.com)

4. Host (www.sohu.com)

FQDN (Fully Qualified Domain Name)-the full name or fully qualified domain name of a domain

FQDNS = hostname + DNS suffix, such as baidu.com, etc.

3. DNS query types

1. Divide it in terms of query mode

Recursive query: the result obtained by the client can only be success or failure

Iterative query: the DNS server returns the correct address if a client requests data

If the DNS server does not request data, a pointer is returned.

2. Divide it from the content of the query

Forward query: IP address is found by domain name

Reverse query: find the domain name by IP address

Configure the DNS server

1. Installation requirements of DNS server

(1) Windows 2000 Compact 2003 / 2008Server / 2012Server

(2) static IP address

2. The necessary conditions for providing DNS services

(1) the server has a fixed IP address

(2) install and start the DNS service

(3) have a zone file, either configure a transponder or configure a root prompt

3. Install the DNS server

(1) install the DNS server role

① configures the IP address of DNS server; check DNS server for ② server role.

(2) New area

① creates a forward lookup; ② creates a reverse lookup.

Administration-add roles or features (DNS server)

4. Resource record

The DNS zone provides the corresponding domain name resolution to the client through resource records.

Resource records: records parsed by DNS server

Resource record description

SOA (initial Authorization record) defines the authoritative name servers in this domain.

NS (name server) represents the authoritative server in a zone and the primary and secondary servers in the zone specified in the SQA

Mapping of FQDN (fully qualified domain names) to IP addresses in the A (host) zone

PTR (pointer) relative to A resource record, PTR record maps IP address to FQDN

MX mail exchanger records that provide message routing to specified mail exchange hosts

SRV (Services) lists the servers that are providing specific services

CNAME (alias) maps multiple names to the same computer for easy access.

Configure the DNS client

1. Configure static DNS server address

2. DHCP server dynamically assigns DNS server address

VI. Transponder

Queries that cannot be parsed by the local DNS server are forwarded to other DNS servers on the network. This local DNS server is called a forwarder.

Forward to ISP DNS server, Beijing Netcom DNS server IP address: 202.106.46.151, 202.106.196.115, 202.106.0.20, 210.82.5.1

7. Root hint

Non-root domain DNS servers can find the root domain DNS server through the root prompt

VIII. DNS area transmission

Primary DNS server, secondary DNS server

In order to reduce the load of a single DNS server, the content of the same DNS area can be saved in multiple DNS servers and realized by regional transmission.

The primary DNS server establishes the primary area, and the auxiliary DNS server establishes the secondary area to maintain the DNS resource records together. Any failure of the DNS server will not affect the use, which is called backup or redundancy.

Note: a major area can have multiple auxiliary areas, and the auxiliary area can also have auxiliary areas.

Zone transfer: the process of copying zone files from the primary DNS server to the secondary DNS server

IX. Subdomain / delegation

Subdomains: you can create subdomains in the zone to expand the domain name space

Delegate: delegate subdomains to other servers for maintenance

The difference between subdomains and delegates:

The resources of the child domain are in the parent zone file, and the authoritative server of the child domain is the authoritative server of the parent zone.

Delegate a separate zone file to assign a new authoritative server to the new domain

1. The child domain shares a zone file with the parent zone, and the authoritative server of the child domain is the authoritative server of the parent zone.

2. Delegate an independent zone file and assign a new authoritative server to the new domain (delegate has its own authoritative server)

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