Table of Contents

1 DNS Configuration Guide· 1-1

Configuring Static Domain Name Resolution· 1-1

Network diagram·· 1-1

Networking and Configuration Requirements· 1-1

Applicable Product Matrix· 1-1

Configuration procedure· 1-1

Complete Configuration· 1-2

Configuration Guidelines· 1-2

Configuring Dynamic Domain Name Resolution· 1-2

Network diagram·· 1-2

Networking and Configuration Requirements· 1-3

Applicable Product Matrix· 1-3

Configuration procedure· 1-3

Complete Configuration· 1-4

Configuration Guidelines· 1-4

Configuring DNS Proxy· 1-4

Network diagram·· 1-4

Networking and Configuration Requirements· 1-4

Applicable Product Matrix· 1-5

Configuration procedure· 1-5

Complete Configuration· 1-6

Configuration Guidelines· 1-6

 

Configuring Static Domain Name Resolution

The static domain name resolution means setting up mappings between domain names and IP addresses. IP addresses of the corresponding domain names can be found in the static domain resolution table when you use applications such as telnet.

Network diagram

Figure 1-1 Network diagram for static domain name resolution

 

Networking and Configuration Requirements

Switch uses the static domain name resolution to access Host with IP address 10.1.1.2 through domain name host.com.

Applicable Product Matrix

Product series	Software version	Hardware version
S3610 Series Ethernet Switches	Release 5301 Release 5303	All versions
S5510 Series Ethernet Switches	Release 5301 Release 5303	All versions
S5500-SI Series Ethernet Switches	Release 1207	All versions except S5500-20TP-SI
	Release 1301	S5500-20TP-SI
S5500-EI Series Ethernet Switches	Release 2102	All versions
S7500E Series Ethernet Switches	Release 6100 Release 6300	All versions
S3500-EA Series Ethernet Switches	Release 5303	All versions

 

Configuration procedure

# Configure a mapping between host name host.com and IP address 10.1.1.2.

<Sysname> system-view

[Sysname] ip host host.com 10.1.1.2

# Execute the ping host.com command to verify that Switch can use the static domain name resolution to get the IP address 10.1.1.2 corresponding to host.com.

 [Sysname] ping host.com

  PING host.com (10.1.1.2):

  56  data bytes, press CTRL_C to break

    Reply from 10.1.1.2: bytes=56 Sequence=1 ttl=128 time=2 ms

    Reply from 10.1.1.2: bytes=56 Sequence=2 ttl=128 time=2 ms

    Reply from 10.1.1.2: bytes=56 Sequence=3 ttl=128 time=2 ms

    Reply from 10.1.1.2: bytes=56 Sequence=4 ttl=128 time=2 ms

    Reply from 10.1.1.2: bytes=56 Sequence=5 ttl=128 time=2 ms

 

  --- host.com ping statistics ---

    5 packet(s) transmitted

    5 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 2/2/2 ms

Complete Configuration

#

 ip host host.com 10.1.1.2

#

Configuration Guidelines

None

Configuring Dynamic Domain Name Resolution

Domain Name System (DNS) is a distributed database used by TCP/IP applications to translate domain names into corresponding IP addresses. With DNS, you can use easy-to-remember domain names in some applications and let the DNS server translate them into correct IP addresses.

Network diagram

Figure 1-2 Network diagram for dynamic domain name resolution

 

Networking and Configuration Requirements

l          The IP address of the DNS server is 2.1.1.2/16 and the name suffix is com.

l          Switch serves as a DNS client, and uses the dynamic domain name resolution and the suffix to access the host with the domain name host.com and the IP address 3.1.1.1/16.

Applicable Product Matrix

Product series	Software version	Hardware version
S3610 Series Ethernet Switches	Release 5301 Release 5303	All versions
S5510 Series Ethernet Switches	Release 5301 Release 5303	All versions
S5500-SI Series Ethernet Switches	Release 1207	All versions except S5500-20TP-SI
	Release 1301	S5500-20TP-SI
S5500-EI Series Ethernet Switches	Release 2102	All versions
S7500E Series Ethernet Switches	Release 6100 Release 6300	All versions
S3500-EA Series Ethernet Switches	Release 5303	All versions

 

Configuration procedure

# Enable dynamic domain name resolution.

<Sysname> system-view

[Sysname] dns resolve

# Specify the DNS server 2.1.1.2.

[Sysname] dns server 2.1.1.2

# Configure com as the name suffix.

[Sysname] dns domain com

# Execute the ping host command on the device to verify that the communication between the device and the host is normal and that the corresponding destination IP address is 3.1.1.1.

[Sysname] ping host

Trying DNS resolve, press CTRL_C to break

 Trying DNS server (2.1.1.2)

  PING host.com (3.1.1.1):

  56  data bytes, press CTRL_C to break

    Reply from 3.1.1.1: bytes=56 Sequence=1 ttl=126 time=3 ms

    Reply from 3.1.1.1: bytes=56 Sequence=2 ttl=126 time=1 ms

    Reply from 3.1.1.1: bytes=56 Sequence=3 ttl=126 time=1 ms

    Reply from 3.1.1.1: bytes=56 Sequence=4 ttl=126 time=1 ms

    Reply from 3.1.1.1: bytes=56 Sequence=5 ttl=126 time=1 ms

 

  --- host.com ping statistics ---

    5 packet(s) transmitted

    5 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 1/1/3 ms

Complete Configuration

#

 dns resolve

 dns server 2.1.1.2

 dns domain com

#

Configuration Guidelines

l          Before performing the above configuration, assume that the switch and the host are reachable to each other and the IP addresses of the interfaces are configured.

l          The DNS client needs to cooperate with the DNS server to obtain a correct IP address through domain name resolution.

Configuring DNS Proxy

A DNS proxy forwards DNS requests and replies between DNS clients and a DNS server.

A DNS client sends a DNS request to the DNS proxy, which forwards the request to the designated DNS server, and conveys the reply from the DNS server to the client.

The DNS proxy simplifies network management. When the DNS server address is changed, you only need to change the configuration on the DNS proxy instead of on each DNS client.

Network diagram

Figure 1-3 Network diagram for DNS proxy

 

Networking and Configuration Requirements

l          Specify Switch A as the DNS server of Switch B (the DNS client).

l          Switch A acts as a DNS proxy. The IP address of the real DNS server is 4.1.1.1.

l          Switch B implements domain name resolution through Switch A.

Applicable Product Matrix

Product series	Software version	Hardware version
S5500-SI Series Ethernet Switches	Release 1207	All versions except S5500-20TP-SI
	Release 1301	S5500-20TP-SI
S5500-EI Series Ethernet Switches	Release 2102	All versions
S7500E Series Ethernet Switches	Release 6100 Release 6300	All versions

 

Configuration procedure

1)        Configure the DNS proxy

# Specify the DNS server 4.1.1.1.

<SwitchA> system-view

[SwitchA] dns server 4.1.1.1

# Enable DNS proxy.

[SwitchA] dns proxy enable

2)        Configure the DNS client

# Enable the domain name resolution function.

<SwitchB> system-view

[SwitchB] dns resolve

# Specify the DNS server 2.1.1.2.

[SwitchB] dns server 2.1.1.2

3)        Configuration verification

# Execute the ping host.com command on Switch B to verify that the communication between the device and the host is normal and that the corresponding destination IP address is 3.1.1.1.

[SwitchB] ping host.com

Trying DNS resolve, press CTRL_C to break

 Trying DNS server (2.1.1.2)

  PING host.com (3.1.1.1):

  56  data bytes, press CTRL_C to break

    Reply from 3.1.1.1: bytes=56 Sequence=1 ttl=126 time=3 ms

    Reply from 3.1.1.1: bytes=56 Sequence=2 ttl=126 time=1 ms

    Reply from 3.1.1.1: bytes=56 Sequence=3 ttl=126 time=1 ms

    Reply from 3.1.1.1: bytes=56 Sequence=4 ttl=126 time=1 ms

    Reply from 3.1.1.1: bytes=56 Sequence=5 ttl=126 time=1 ms

 

  --- host.com ping statistics ---

    5 packet(s) transmitted

    5 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 1/1/3 ms

Complete Configuration

l          Configure Switch A (DNS proxy)

#

 dns proxy enable

 dns server 4.1.1.1

#

l          Configure Switch B (DNS client)

#

 dns resolve

 dns server 2.1.1.2

#

Configuration Guidelines

l          Before performing the above configuration, make sure that the switch and the host are reachable to each other and the IP addresses of the interfaces are configured.

l          The DNS client needs to contact the DNS server to obtain a correct IP address through domain name resolution.