Cisco Systems 2.5 - page 162

Chapter6 Edit Interface/Connection
Connection: Analog Modem
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Cisco Router and Security Device Manager 2.5 User’s Guide
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Subnet Mask
Enter the subnet mask. The subnet mask specifies the portion of the IP address
that provides the network address. This value is synchronized with the network
bits. Obtain the value of the subnet mask or the network bits fr om your network
administrator or service provider.
Subnet Bits
Alternatively, enter the network bits to specify how many bits in the IP address
provide the network address.
Authentication
Click if you need to enter CHAP or PAP authentication information.
Dynamic DNS
Enable dynamic DNS if you want to update your DNS servers automatically
whenever the WAN interface IP address changes.
Note This feature appears only if supported by the Cisco IOS release on your router.
To choose a dynamic DNS method to use, do one of the following:
•Enter the name of an existing dynamic DNS method.
Enter the name in the Dynamic DNS Method field exactly as it appears in the
list in Configure > Additional Tasks > Dynamic DNS Methods.
•Choose an existing dynamic DNS method from a list.
Click the drop-down menu and choose an existing method. A window with a
list of existing dynamic DNS methods opens. This menu choice is available
only if there are existing dynamic DNS methods.
•Create a new dynamic DNS method.
Click the drop-down menu and choose to create a new dynamic DNS method.
To clear an associated dynamic DNS method from the interface, choose None
from the drop-down menu.