Test-Um NT750 - Manual (Page 21)

LanScaper
TM
Appendix B: Internet Protocol Definitions
ARP = Address Resolution Protocol - Used to determine Ethernet (MAC) address when a device
starts to communicate with another. The IP address is known and a broadcast is used to request the
specific IP addressed device to respond with its MAC address, so further communication can be
specifically addressed between the two.
DHCP
DNS
Gateway
IP
IPAddress
ISP
LAN
Network Mask
= Dynamic Host Configuration Protocol - Used when a new IP device is added to a LAN
and it needs to get information about the IP addresses used on that LAN. One DHCP server must
be present on the LAN to provide a response to a DHCP request transmitted to a broadcast address
and inform the new device of several configuration details. A DHCP server is not required on a
LAN, but if it does not exist, all the devices on the LAN must be manually configured. Much
information can be provided by the DHCP server, the LanScaper™ requests and uses:
- an IP address for itself (My IP)
- the IP address of the DHCP server on the LAN
- the Netmask in use
- the IP address of the Router on the LAN
- the IP address of the DNS server accessible from the LAN
= Domain Name Server - Provides translation of URL addresses (www.yahoo.com) to IP
addresses (66.218.71.89), so that access to the internet devices can be requested using human-
understandable identifiers. DNS servers are found on the internet, and thus are of interest to the
LanScaper™ because accessing (PINGing) the DNS server proves that the LanScaper™ can access
a device on the WAN.
= Router - see below
= Internet Protocol - Actually TCP/IP = Transmission Control Protocol/Internet Protocol, but
commonly abbreviated to IP. Communications addressing scheme defined by DARPA (Defense
Advanced Research Projects Agency) to control the publicly accessed internet network.
- Specific number assigned to a single device to allow it to be uniquely identified on the
network to which it is connected. On a LAN, the IP address must be within the range of addresses
defined for that LAN by the Network Mask in use. On the internet, all IP addresses must be
universally unique to allow addressing that specific device. IP addresses consist of 4 hexadecimal
digits that are commonly written in "dotted decimal" format. 192.168.254.4 is an example. Note
that each set of decimal numbers divided by the periods must be in the range of 0-255 as they
represent hexadecimal values of 00-FF.
= Internet Service Provider - Commercial supplier of access mechanisms for public access to
the internet.
= Local Area Network - Connection mechanism for a business, home, school or any group of
devices to communicate with each other. In the LanScaper™ case, it is a group of computers,
printers, routers and possibly other devices connected by Ethernet. Distinct from the WAN due to
the IP addressing in a "Subnet".
= Subnet Mask - IP addressing scheme that divides the entire IP address network
into smaller sections (Subnets). In the case of the LanScaper™, the Network mask is used to
identify an IP address as being located either on the LAN (local subnet) or on the Internet, and
therefore accessed over the WAN.