Huawei Quidway S5600 Series Operation Manual page 984

Operation Manual - DNS
Quidway S5600 Series Ethernet Switches-Release 1510
User program User program
Figure 1-1 Dynamic domain name resolutio
The resolver and cache comprise the DNS Client. The user program run on the same
machine as the DNS Client, while the DNS Server and the DNS Client must run on
different machines.
Dynamic domain name resolution allows the DNS Client to store latest mappings
between name and IP address in the dynamic domain name cache. There is no need to
send a request to the DNS Server for the same mapping next time. The aged mappings
are removed from the cache after some time, and latest entries are required from the
DNS Server. The DNS Server decides how long a mapping is valid, and the DNS Client
gets the information from the DNS messages.
II. DNS suffixes
The DNS Client normally holds a list of suffixes which can be defined by the users. It is
used when the name to be resolved is not complete. The resolver can supply the
missing part, which is call automatic DNS suffix. For example, a user can configure com
as the suffix for aabbcc.com. The user only needs to type aabbcc to get the IP address
of aabbcc.com. The resolver can add the suffix and delimiter before passing the name
to the DNS Server.
If there is no dot in the domain name, such as "aabbcc", the resolver will consider
this as a host name and add the suffix before processing. The original name such
as aabbcc is used if all DNS lookups fail.
If there is a dot in the domain name, such as "www.aabbcc, the resolver will use
this domain name to do DNS lookup first before adding any suffix.
If the dot is at the end of the domain name, such as "aabbcc.com.", the resolver
will delete the dot at the end before doing DNS lookup. If the lookup fails, the
resolver will add suffix to do DNS lookup..
Currently, S5600 series switches support static and dynamic domain name services on
the DNS Client.
Request Request
Resolver Resolver
Response Response
Save Save
Cache Cache
DNS Client DNS Client
Huawei Technologies Proprietary
Request Request
Response Response
DNS Server DNS Server
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Chapter 1 DNS Configuration