Ns (Name Server) Record; Mx (Mail Exchange) Record; Reverse Lookup; Forwarding - Panasonic DP-8020E Service Manual

9.5.8.

NS (Name Server) Record

The Name Server record specifies the other name servers for a domain. The syntax for a name server
record is shown below:
<domain> IN NS <nameserver host>
An example of a name server record follows below:
@ IN NS nwmgr.pcc.co.jp
The "@" symbol indicates the local domain. The server "nwmgr" in the domain "pcc.co.jp" is the name
server.
9.5.9.

MX (Mail Exchange) Record

The Mail Exchange (MX) record specifies the name of the host that processes mail for this domain. If you
list multiple mail servers, you can set a preference number (value) that specifies the order in which the mail
server should be used. Note that lower values indicate higher precedence, and that mailers are supposed
to randomize same-value MX hosts so as to distribute the load evenly if values are equal. If the first
preferred mail server does not respond, the second one is contacted, and so on.
If you want a host to receive its own mail, you should create an MX record for your host's name, pointing at
your host's name. The syntax of this record is shown below:
<domain> IN MX <preference> <mailserver host>
For a more detail, please refer to RFC974 document at URL http://www.ietf.org/.

9.5.10. Reverse Lookup

This is a special domain for allowing address to name mapping. As Internet host addresses do not fall
within domain boundaries, this special domain was formed to allow inverse mapping. The IN-ADDR.ARPA
domain has four labels preceding it. These labels correspond to the 4 octets of an Internet address. All four
octets must be specified even if an octet contains zero. The Internet address 128.32.0.4 is located in the
domain 4.0.32.128.IN-ADDR.ARPA. This reversal of the address is awkward to read but allows for the
natural grouping of hosts in a network.

9.5.11. Forwarding

A Slave Server is a server that always forwards queries it cannot satisfy from its cache, to a fixed list of
forwarding servers instead of interacting with the name servers for the root and other domains. The queries
to the forwarding servers are recursive queries. There may be one or more forwarding servers, and they are
tried in turn until the list is exhausted. A Slave and forwarder configuration is typically used when you do not
wish all the servers at a given site to interact with the rest of the Internet servers. A typical scenario would
involve a number of workstations and a departmental timesharing machine with Internet access. The
workstations might be administratively prohibited from having Internet access. To give the workstations the
appearance of access to the Internet domain system, the workstations could be Slave servers to the
timesharing machine, which would forward the queries and interact with other name servers to resolve the
query before returning the answer. An added benefit of using the forwarding feature is that the central
machine develops a much more complete cache of information that all the workstations can take advantage
of. The use of Slave mode and forwarding is discussed further under the description of the named bootfile
commands.
There is no prohibition against declaring a server to be a slave even though it has primary and/or secondary
zones as well; the effect will still be that anything in the local server's cache or zones will be answered, and
anything else will be forwarded using the forwarders list.
For more detail, please refer to published book (i.e. DNS and BIND etc) provided from O' Reilly &
Associates, Inc.
Ver. 1.0
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DP-8020E/8020P/8016P
SEP 2006