Agilent Technologies N8201A manual Glossary

User’s Guide

7 Glossary

Auto-IPAuto-IP is a method used by a device to self select an IP address. When a device is using Auto-IP, it randomly selects an address of the form 169.254.x.x. If another device is already using that address, it selects another random address, and continues to select new addresses until it finds one that is not being used by any other instrument.

Cross-Over Cable A cross-over cable can be used to connect two devices directly to each other, without a network switch or any other hardware in-between. It is common to use static IP addresses when devices are connected using a cross-over cable, because there is no DNS, and there are no other devices on the connection that could cause an IP address conflict.

Default Gateway The default gateway is used by a device to communicate with devices that have IP addresses that are on different subnets. This would usually be the IP address of the router that connects the device’s subnet to the rest of the network.

DHCP [Dynamic Host Configuration Protocol] In order to avoid IP address conflicts, and to simplify the process of connecting devices to a network, larger networks will sometimes use DHCP to assign IP addresses to devices.

When a device is configured to use DHCP, it attempts to communicate with the DHCP server when it is powered on. If it is able to communicate with the server, it asks the server for the correct network settings (including IP Address, Subnet Mask, Gateway, and so on) to communicate on the network. If the device is unable to communicate with the DHCP server, it will either go into a failure mode, or (if configured to do so) it will attempt to assign itself an IP address. (See Auto-IP)

Because the IP address assigned to an instrument can be different every time it is powered on, you cannot remember the IP address and expect to always be able to use that address to communicate with the instrument. However, networks using DHCP will often also use DNS, which can allow you to communicate with a device using a hostname that will stay the same, even if the device’s IP address has changed.

DHCP Server The DHCP server responds to devices’ requests for network settings. It is responsible for ensuring that no two devices attempt to use the same IP address.

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