114 Agilent N8201A Performance Downconverter Synthetic Instrument Module, 3 Hz to 26.5 GHz
7Glossary
DNS [Domain Name Server] A domain name server allows someone to communicate
with a device using the device’s hostname. When a device joins a network, it tells the
domain name server its hostname and its IP address. When a hostname is used, the domain
name server is asked which IP address the name corresponds to, and that address is then
used to communicate with the instrument.
If the IP address of the device changes, it can request that its entry in the domain name
server be updated. Any following requests that use the same hostname as before, will be
sent to the new address.
Hostname A hostname is a unique name that can be used to communicate with a device
on a network. Hostnames are commonly used in situations where devices have their
addresses assigned to them using DHCP.
Hostnames can only be used if there is some way that the network can keep track of which
hostname corresponds to an instrument. This is usually done using DNS.
Networks without DNS have no way to associate a hostname with a device. This is often
true of small private LAN networks (for example, a network consisting of two devices
connected using a cross-over cable, or through a simple router). In these cases, it is
probably easiest to use static IP addresses.
IP Address [Internet Protocol Address] An IP add ress is a unique number assigned to
a device which is used to send or receive data to and from other devices.
The most common IP addresses are IP Version 4. These addresses are usually written as
four numbers (from 1 to 255) separated by peri ods. For example, 192.168.1.1 and
169.254.12.34 and 141.121.84.241 are all IP addresses.
A device’s IP address can be assigned to it manually (See Static IP Address), assigned to it
by another computer (See DHCP) or can be self-determined (See Auto-IP).
IP Address Conflict An IP address conflict occurs whe n two devices attempt to join the
same network with the same IP address. When this happens, it may become impossible to
communicate with either instrument over the LAN. Using dynamically assigned addresses
can help avoid this problem. (See DHCP or Auto- IP.)
LAN [Local Area Network] A LAN is a network of devices connected to each other
using LAN cables and network switches.
Network Switch A network switch is used to connect several devices together to form a
LAN. It has several LAN ports that LAN cables can be connected to.
If it is necessary to create a network with more devices than can connect to a single
network switch, one (or more) switches can be attached to the first switch.
Private LAN A private LAN network is defined as a local area network in which
LAN-enabled instruments and Windows PCs are not connected to a site LAN (workgroup
LAN, Intranet, or enterprise LAN). When using a private LAN, the designer of the LAN is
responsible for defining all private LAN parameters.