H3C S3600 Series User Manual

Operation Manual – DNS
H3C S3600 Series Ethernet Switches-Release 1510 Chapter 1
DNS Configuration
1-2
User program Resolver
Cache
Request
Response
Save Read
DNS Server
DNS Client
Request
Response
User program Resolver
Cache
Request
Response
Save Read
DNS Server
DNS Client
Request
Response
n Figure 1-1 Dynamic domain name resolutio
Figure 1-1 shows the relationship between user program, NDS Client, and DNS Server.
The resolver and cache comprise the DNS Client. The user program and DNS Client
can run on the same machine or different machines, while the DNS Server and the
DNS Client usually 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 a repeated query request 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 DNS messages.
II. DNS suffixes
The DNS Client normally holds a list of suffixes which can be defined by users. It is
used when the name to be resolved is not complete. The resolver can supply the
missing part. 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.
z If there is no dot in the domain name, such as aabbcc, the resolver will consider
this as a host name and add a DNS suffix before processing. The original name
such as aabbcc is used if all DNS lookups fail.
z 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. If the lookup fails, the resolver adds a
DNS suffix for another lookup.
z If a dot is at the end of the domain name, such as “aabbcc.com.”, the resolver will
consider this as a fully qualified domain name and return the result, success or
failure. Hence, the dot (.) is called the terminating symbol.
Currently, the device supports static and dynamic DNS services.

H3C S3600 Series Specifications

General

Brand	H3C
Model	S3600 Series
Category	Switch
Language	English