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Domain name server enhancements, Dns caching – Allied Telesis AR300 series User Manual

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Software Release 2.3.1

7

Software Release 2.3.1
C613-10325-00 REV B

Figure 2: Example output from the SHOW INTERFACE command for a specific interface.

Domain Name Server Enhancements

Software Release 2.3.1 includes two enhancements to Domain Name Server
(DNS) functionality:

The router can now store recently obtained DNS information in a cache.

The router can now be configured to use a range of DNS servers. Server
selection is based on the host name that is being resolved.

DNS Caching

DNS caching allows the router to store recently requested domain or host
addresses so they can be quickly retrieved if an identical DNS request is
received. DNS caching reduces traffic on the Internet and improves
performance for both DNS and DNS relay under heavy usage. The DNS cache
is of a limited size, and times out entries after a specified period of up to 60
minutes.

When a domain or host is requested, the cache is searched for a matching entry.
If a match is found, a response is sent to the requesting PC or host. If a
matching entry is not found, a request will be sent to a remote server.

First, add a DNS server to the list of DNS servers used to resolve host names
into IP addresses, using the command:

ADD IP DNS [DOMAIN={ANY|domain-name}] {INTERFACE=interface|

PRIMARY=ipadd [SECONDARY=ipadd]}

Interface.................. bri0

ifIndex.................. 3

ifMTU.................... 1712

ifSpeed.................. 144000

ifAdminStatus............ Up

ifOperStatus............. Swapped out

ifLinkUpDownTrapEnable... Disabled

TrapLimit................ 20

Interface Counters

ifInOctets .................. 52190 ifOutOctets ................. 52190

ifInUcastPkts ................ 3070 ifOutUcastPkts ............... 3071

ifInNUcastPkts .................. 0 ifOutNUcastPkts ................. 0

ifInDiscards .................... 0 ifOutDiscards ................... 0

ifInErrors ...................... 0 ifOutErrors ..................... 0

Table 1: New parameter displayed in the output of the SHOW INTERFACE
command.

Parameter

Meaning

ifOperStatus

The current operational state of the interface; one of “Up”,
”Down”, “Testing”, or “Swapped Out”.

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