D-Link DES-3528 - xStack Switch - Stackable, Руководство пользователя, Страница: 147 / 322

xStack
®
DES-3528/DES-3552 Series Layer 2 Stackable Fast Ethernet Managed Switch User Manual
146
Parameter Description
Gateway IP Address
Enter the IP address of the gateway.
Gateway MAC
Address
Enter the MAC address of the gateway.
Ports
Specify the switch ports for which to configure this ARP Spoofing Prevention settings. Click
the
All Ports
check box to configure this entry for all ports on the Switch.
DNS Relay
Computer users usually prefer to use text names for computers for which they may want to open a connection.
Computers themselves, require 32 bit IP addresses. Somewhere, a database of network devices’ text names and their
corresponding IP addresses must be maintained.
The Domain Name System (DNS) is used to map names to IP addresses throughout the Internet and has been
adapted for use within intranets.
For two DNS servers to communicate across different subnets, the
DNS Relay
of the Switch must be used. The DNS
servers are identified by IP addresses.
Mapping Domain Names to Addresses
Name-to-address translation is performed by a program called a Name server. The client program is called a Name
resolver. A Name resolver may need to contact several Name servers to translate a name to an address.
The Domain Name System (DNS) servers are organized in a somewhat hierarchical fashion. A single server often
holds names for a single network, which is connected to a root DNS server - usually maintained by an ISP.
Domain Name Resolution
The domain name system can be used by contacting the name servers one at a time, or by asking the domain name
system to do the complete name translation. The client makes a query containing the name, the type of answer
required, and a code specifying whether the domain name system should do the entire name translation, or simply
return the address of the next DNS server if the server receiving the query cannot resolve the name.
When a DNS server receives a query, it checks to see if the name is in its sub domain. If it is, the server translates the
name and appends the answer to the query, and sends it back to the client. If the DNS server cannot translate the
name, it determines what type of name resolution the client requested. A complete translation is called recursive
resolution and requires the server to contact other DNS servers until the name is resolved. Iterative resolution
specifies that if the DNS server cannot supply an answer, it returns the address of the next DNS server the client
should contact.
Each client must be able to contact at least one DNS server, and each DNS server must be able to contact at least
one root server.
The address of the machine that supplies domain name service is often supplied by a DHCP or BOOTP server, or can
be entered manually and configured into the operating system at startup.
DNS Relay Global Settings
To configure the DNS function on the Switch, click
L3 Features > DNS Relay > DNS Relay Global Settings
, which
will open the
DNS Relay Global Settings
window, as seen below: