What is a DHCP Client ID?

What is a DHCP Client ID?


The DHCP protocol is the most common way that home and small office networks get their IP addresses.  Typically, a network administrator will assign a pool of available addresses to the DHCP server on the network’s router or access point. When a device joins the network, it sends a request for an address to the server, which assigns one from its pool and returns it in return. Devices can also be assigned specific static IP addresses if they need them – but this is less common. This article explains how you can set up your own DHCP server on Windows 7 or 8 to provide IP Addresses for devices on your local area network (LAN).

When a computer joins the network, it has to find an IP address that isn’t already in use on the network.  The DHCP server is responsible for making this happen. It maintains a list of the devices that have been assigned addresses and which addresses it has made available for assignment via DHCP.

What is a DHCP Client ID?

A DHCP Client ID is also known as an IP Client ID. This identification can be found on the ARP/DHCP tab in the IP Configuration Settings of the Network Adapter Properties Window. The DHCP Client ID is composed of four hexadecimal numbers that are used to identify a device to provide basic network services.

A DHCP Client ID is essentially a number that’s used by the Dynamic Host Configuration Protocol to identify your device. The DHCP Client ID acts as the media access control (MAC) address for your device. When you connect to a network, your system requests an Internet protocol configuration from a Dynamic Host Configuration Protocol server. The DHCP server uses the DHCP Client ID to identify individual devices that are connected to the network and assigns IP addresses to them.

How many types of DHCP Client IDs are there?

There are three types of DHCP Client IDs: the DUID, the client-id, and the link-local address.

A DHCP Unique Identifier (DUID) is the standard way to identify devices when obtaining an IP address using DHCP. It can be used to provision, or configure, network devices when their identities are not known at the time of configuration. A DUID consists of two parts: a two-octet type field, which identifies the ID as a DUID, followed by a variable number of octets that are unique to each device.

A DHCP Client ID is a unique identifier for a computer or other device that obtains an IP address from a DHCP server, as opposed to getting the IP address from the manual configuration. A client-id does not contain any personally identifiable information, and it can be used with both static and dynamic addressing. It is often assigned by the DHCP server when a device requests an IP address.

A link-local address is also known as a ‘link-layer or MAC-layer address and, although not strictly speaking an IP address, it has identical properties. It consists of eight four-octet fields that are set to binary zeroes, with the fields displaying as filled circles in Microsoft Windows.

Why should I care about my DHCP Client ID?

A DHCP Client ID is a unique number assigned to your network card. It allows you to connect to and use certain information or features of the Internet if those services require an account. For example, if you use Spotify for music streaming, it will ask you for your username and password during the first login. If you don’t have an account, then the site will assign you a random Client ID that it can store as necessary.  However, if you already have an account with your own Client ID, then it will know that you’re the same person and log in automatically. Many other services like Gmail, Twitter, or your email account rely on this feature to work.

What are the dangers of not having a DHCP client ID?

A DHCP client ID is necessary for a device to receive an address from a DHCP server. If the device does not have its own DHCP client ID, it will not be able to request an IP address – which means that the device won’t be able to connect to the internet or any other devices on your network. This will affect your home users’ connectivity and have wide-ranging implications for you as a network administrator.

The most important reasons to set a DHCP client ID are to reduce network congestion and to prevent IP address duplication. Leaving the default ‘DHCP assigned address’ option alone will generate your device’s MAC address as its type of identifier, which acts just like an IP address when requesting an IP configuration from the DHCP server. This means that it uses the same pool of already registered IP addresses as any other device using that MAC address.


The DHCP Client ID is a unique identifier that your computer broadcasts to let the router know which device you’re using. It also tells other devices on the network who should provide internet access and where they can find it. For this reason, we recommend that all of our customers have one configured in their routers for optimum performance. As with any type of security or safety measure, there are risks associated with not configuring a DHCP Client ID if you don’t want somebody else logging into your WiFi from outside your home or office building.  You can change the DHCP Client ID to any value, but be aware that if you share your network with others it may cause performance issues. This is because different devices have different needs for internet access. If all devices are broadcasting their own individual Client IDs, then they’ll each compete for the same bandwidth because there’s no way to prohibit one device from accessing the internet.

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