Vpn (Virtual Private Network); Qos (Quality Of Service); Ping; Nslookup - Furuno Felcom 250 Service Manual

Appendix 4. Abbreviations

VPN (Virtual Private Network)

Internet has communications established by an unspecified number of users where each
of the users selects an appropriate route for him/herself. However, it is true that the
security for the communication route is not being sufficiently considered.
The reason is because communications are not made via LAN connections using
dedicated lines.
Based on such circumstances, VPN has been developed as a technology for using the
Internet line by ensuring the security of the communication by assigning IPsec or PPTP
for specific users.
The information security is improved by making a PC located in a physically long
distance seem as if it is located within the LAN network.

QoS (Quality of Service)

A technology for reserving a specific band within the network for a specific
communication case in order to guarantee a certain communication speed. It is an
important technology used for services where communication delay or interruption is
unacceptable such as audio or video real time delivery or TV phone, etc.

Ping

A tool used for confirming whether another computer located at a long distance is
connected to the network or not. Ping exchanges 2 messages – "echo request" which
requests for a response from the counterparty equipment and "echo response" which
sends a response for an echo request using ICMP (Internet Control Message Protocol).
In normal cases, the network between hosts will be determined as operating normally if
the ping command is executed in a normal manner. It can also easily measure the
network performances, too.
If an error occurs, it can be assumed that some kind of network failure has occurred.
The simplest usage of the Ping command, for example, is to specify the name or the IP
address for the host you wish to confirm its communication status upon the command
prompt screen.
For example, if you type in; "ping 192.172.1.1", a response such as the following will
be sent back from the IP address you had specified here; "Reply from 192.172.1.1: bytes
= 32 time < 10 ms."
If you type in "ping", the ping command options will be displayed.

nslookup

A basic command used for DNS service troubleshooting, etc. The domain name server
host names or the host names for the domains you had entered will be displayed as
corresponding to each IP address.
For example, type in "nslookup google.co.jp" or "nslookup" in the command prompt
screen, and then specify the type to be recorded; set typ = a, mx, ns.
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