328 CHAPTER 21: CONFIGURING IP APPLICATION
By default, the system executes static ARP mapping.
Static ARP mapping items are valid as long as the router works normally, but
dynamic ARP mapping items are valid for only 20 minutes.
Display and Debug ARP Tabl e 359 Display and Debug ARP
Configure Domain Name Resolution (DNS)
The TCP/IP Extranet not only provides an IP address to locate a device, but also
designs a specific character-string host naming mechanism. This system uses a
layered naming mode, designating a meaningful name for a device on the
Internet. There is a domain name resolution server on the network to associate the
domain name to the corresponding IP address. As a result, the user can use the
easy-to-remember, meaningful domain name instead of the complex IP address.
Domain name resolution includes dynamic resolution and static resolution, which
can supplement each other. In the resolution of a domain name, first use static
resolution. If it fails, then use dynamic resolution. Some common domain names
can be put into static domain name resolution table, which greatly increases the
efficiency of domain name resolution.
s domain name resolution requests. The server firstly resolves the domain name
inside its own database, and submits it to superior domain name resolution server
if the domain name is not within local domain, till the resolution is completed. The
result can either be an IP address, or a non-existing domain name, which will be
fed back to the user.
Static resolution sets relationships between domain names and IP addresses
manually. When a client requires an IP address corresponding to a domain name, it
searches the static domain name resolution table for this designated domain name
to get the corresponding IP address
Configure Static Domain
Name Resolution Static domain name resolution is conducted through static domain name
resolution table, similar to the host file under Windows 95/98 operating system.
The router can obtain the IP addresses of common domain names by checking this
table. Meanwhile, it is easier for the user to remember host names than the highly
abstract IP address to access the corresponding device.
Domain name resolution configuration include:
■Add/delete static domain name resolution table item
1Add/delete static domain name resolution table item
Perform the following task in system view.
Tabl e 360 Add/delete static domain name resolution table item
Operation Command
Display ARP mapping table display arp [ verbose [
ip-address ] ]
Clear dynamic ARP information reset arp-cache
Turn on ARP commission information debugging arp
Operation Command
Add static domain name resolution table item ip host domain-name ip-address