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When a PC user types a domain name into a browser, the PC
must first send a request to a DNS server to obtain the
equivalent IP address. The DNS server will attempt to look up
the domain name in its own database, and will communicate
with higher-level DNS servers when the name cannot be found
locally. When the address is found, it is sent back to the
requesting PC and is referenced in IP packets for the remainder
of the communication.
Click on the
Enable
or
Disable
radio button to manage the
DNS feature.
DNS Relay Poll Status:
By placing a check in this box the
software will send out regular test messages to the DNS
servers to make sure that they remain up.
DNS Relay Poll Timeout:
Enter a value (number of
minutes) after which the polling of the DNS server will time
out.
DNS Server IP Address:
Enter the DNS server IP
address.
Priority:
Select a priority level from the drop-down list.
Click on the
Add
button to add the entry into the table.
Click on the
Submit
button when completed and make sure
to
Commit & Reboot
.
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9.7 Blocked
Protocols
Click on the
Blocked Protocols
link to view the list of protocols.
This page is used to block or unblock protocols running across
the system. Place a check in the box of particular protocol in
order to block it.
The ADSL/Ethernet router is capable of sending and receiving
information in a variety of protocol formats. The Blocked
Protocols feature enables you to prevent the ADSL/Ethernet
router from passing any data that uses a particular protocol.
Unlike the IP Filter feature, you cannot specify additional criteria
for blocked protocols, such as particular users or destinations.
However, when you are certain that a particular protocol is not
needed or wanted on your network, this feature provides a
convenient way to discard such data before it is passed.
Note
: Blocking certain protocols
may disrupt or disable your
network communication or
Internet access. If you are
unfamiliar with how your network
or Internet connection uses these
protocols, contact your ISP before
disabling
.
PPPoE:
Point to Point
Protocol over Ethernet.
Many DSL modems use
PPoE to establish and
maintain a connection
with a service provider.
PPoE provides a means
of logging in to the ISPs
servers so that they can
authenticate you as a
customer and provide you access to the Internet. Check
with your ISP before blocking this protocol.
IP Multicast
: IP Multicast is an extension to the IP protocol.
It enables individual packets to be sent to multiple hosts on
the Internet, and is often used for handling e-mail mailing
lists and teleconferencing and videoconferencing.