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You can configure a domain name suffix list so that the resolver can use the list to supply the missing
part of an incomplete name. For example, you can configure
com
as the suffix for aabbcc.com. The
user only needs to enter
aabbcc
to obtain the IP address of
aabbcc.com
. The resolver adds the
suffix and delimiter before passing the name to the DNS server.
The name resolver handles the queries based on the domain names that the user enters:
•
If the user enters a domain name without a dot (.) (for example, aabbcc), the resolver considers
the domain name as a host name. It adds a DNS suffix to the host name before performing the
query operation. If no match is found for any host name and suffix combination, the resolver
uses the user-entered domain name (for example, aabbcc) for the IP address query.
•
If the user enters a domain name with a dot (.) among the letters (for example, www.aabbcc),
the resolver directly uses this domain name for the query operation. If the query fails, the
resolver adds a DNS suffix for another query operation.
•
If the user enters a domain name with a dot (.) at the end (for example, aabbcc.com.), the
resolver considers the domain name an FQDN and returns the successful or failed query result.
The dot at the end of the domain name is considered a terminating symbol.
Static domain name resolution
Static domain name resolution means manually creating mappings between domain names and IP
addresses. For example, you can create a static DNS mapping for a device so that you can Telnet to
the device by using the domain name.
After a user specifies a name, the device checks the static name resolution table for an IP address. If
no IP address is available, it contacts the DNS server for dynamic name resolution, which takes
more time than static name resolution. To improve efficiency, you can put frequently queried
name-to-IP address mappings in the local static name resolution table.
DNS proxy
The DNS proxy performs the following operations:
•
Forwards the request from the DNS client to the designated DNS server.
•
Conveys the reply from the DNS server to the client.
The DNS proxy simplifies network management. When the DNS server address is changed, you can
change the configuration on only the DNS proxy instead of on each DNS client.
DDNS
DNS provides only the static mappings between domain names and IP addresses. When the IP
address of a node changes, your access to the node fails.
Dynamic Domain Name System (DDNS) can dynamically update the mappings between domain
names and IP addresses for DNS servers.
To use DDNS, a user must access the website of a DDNS service provider and register an account.
When its IP address changes, the user, as a DDNS client, sends a DDNS update request to the
DDNS server to update the mapping between its domain name and IP address. When receiving the
update request, the DDNS server verifies the following:
•
The account information is correct.
•
The domain name to be updated belongs to the account.
If the DDNS client passes the verification, the DDNS server tells the DNS server to re-map the
domain name and the IP address of the DDNS client.
