Configuring Domain Name Resolution; Configuring Static Domain Name Resolution - 3Com 4200G 12-Port Configuration Manual

2) The DNS resolver looks up the local domain name cache for a match. If a match is
found, it sends the corresponding IP address back. If not, it sends the query to the DNS
server.
3) The DNS server looks up its DNS database for a match. If no match is found, it sends
a query to a higher-level DNS server. This process continues until a result, success or
failure, is returned.
4) The DNS client performs the next operation according to the result.
Figure 1-1 Dynamic domain name resolution
Figure 1-1 shows the relationship between user program, DNS client, and DNS server.
The resolver and cache comprise the DNS client. The user program and DNS client run on
the same device, while the DNS server and the DNS client usually run on different devices.
Dynamic domain name resolution allows the DNS client to store latest mappings between
name and IP address in the dynamic domain name cache of the DNS client. 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.
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
(automatic domain name addition). 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 a DNS 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 and aabbcc., the resolver
will directly use this domain name to do DNS lookup first. If the lookup fails, the
resolver adds a DNS suffix for another lookup.

Configuring Domain Name Resolution

Configuring Static Domain Name Resolution

Follow these steps to configure static domain name resolution:
1-2