DHCP Guide: Everything to Know About DHCP Management, Monitoring, and Configuration

By Staff Contributor on March 4, 2020

As all IT teams know, Dynamic Host Configuration Protocol (DHCP) management and monitoring is crucial because without proper DHCP management, your networking environment can end up as a complete mess. DHCP underpins all the distribution of IP addresses and is a key part of configuring subnet masks, default gateways, and DNS server information. DHCP servers assign IP addresses automatically, which can usually save IT administrators time (as they don’t need to go through this process manually). But if DHCP configuration is incorrect, or mismanaged, then the entire automated process becomes a big headache.

One of the easiest ways to simply manage DHCP and keep track of everything is to use professional tools. These tools can help you to monitor how your DHCP servers are performing, and whether there are any problems with IP address assignment or management. My top choice of tools for these tasks are SolarWinds® IP Address Manager and the Engineer’s Toolset, as they’re quick and easy to set up and integrate, and also include a broad range of features to ensure your DHCP management and configuration is streamlined and simple.

What Is DHCP?
What Is the Importance of DHCP Configuration? 5 Top Benefits
What Is DHCP Monitoring and DHCP Management Used For?
DHCP Monitoring and DHCP Management Best Practices
Get Started with DHCP By Using the Right Tools

What Is DHCP?

DHCP stands for Dynamic Host Configuration Protocol, and it’s a protocol used in the process of assigning IP addresses to devices. It’s important to note the word “Protocol,” as this gives a clue as to what it does: it’s a process rule for how IP addresses are assigned, and it works in the same way for each device or network. It also keeps track of all the IP addresses on your network, and any subnets requiring IP addresses.

There are two main types of computers relevant for DHCP. First, individual computers, called hosts, are what you think of when you consider working computers, your own laptop, and so on. The second type of computer is a server, which helps to process and send data for other computers.

DHCP servers are those with several IP addresses stored and ready to assign to hosts when they join the network. Another key part of the DHCP name you need to understand is the word “Dynamic.” In this context, dynamic means IP addresses are assigned on an “as needed” basis, or dynamically, when a computer requests an IP address from the pool of IP addresses stored on the DHCP server. DHCP servers, by default, assign IP addresses for five days, which means after this point a new IP address will be assigned. This process occurs automatically.

DHCP servers are able to assign IPv4 addresses to clients you have on your network. A different type of server, called a RADVD server, or DHCPv6 server, can assign IPv6 addresses.

What Is the Importance of DHCP Configuration? 5 Top Benefits

DHCP configuration is essentially a matter of defining the scope of how your DHCP server will work. There are several steps to follow as you set up and configure your DHCP server:

  1. When you set up a DHCP server, you first need to determine whether you want to set it up on the current network, on a new subnet, or for an already-existing subnet.
  2. Then, you need to configure a static IP address for the DHCP server. A dynamic IP address cannot be used for the server. You also need to spend some time choosing the settings for the DHCP IP address itself, including the subnet mask, default gateway, and network speed.
  3. Next, you need to go through the DHCP server configuration settings. First, you need to choose the starting IP and ending IP address for the range of IP addresses capable of being allocated to DHCP clients. DHCP server configuration also includes specifying the subnet mask for subdividing your IP addresses.
  4. Next, you need to specify the lease time. This is the length of time each IP address will be allocated to a host, and after which it will be returned to the pool of IP addresses on the server to be allocated to other devices.
  5. Finally, to finish the DHCP server configuration process, the default gateway also needs to be specified, and you need to choose a primary and secondary DNS server for the DHCP server.

This process specifies the parameters under which your DHCP server will operate. If you have configured something incorrectly, such as setting default gateways, subnet masks, or IP address ranges, your DHCP server might not work as expected. DHCP configuration is vitally important, as doing it wrong could cause major network disruptions and slowdowns while you figure out the issue.

What Is DHCP Monitoring and DHCP Management Used For?

Once you have your DHCP server installed and configured, you still need to consider the issue of maintenance. This includes changing configurations as needed and monitoring the DHCP server regularly to make sure it’s performing as expected. There are many different metrics and issues admins need to keep an eye on when it comes to the DHCP server.

First, the team needs to ensure the DHCP server is running. Track start time and uptime and check for messages and events coming from the server.

Next, it’s also vital to see if the DHCP is allocating IP addresses as expected. You can check metrics like “total scopes active on the server,” or monitor the number of requests, declines, and releases.

Finally, you need to check how many IP addresses are still available to be allocated to clients, which can help with capacity planning and ensure you don’t run into performance issues or bottlenecks. You must ensure the set “lease time” of each IP address is not too long. If you create leases that are too long, you might end up with assigned but unused IP addresses unavailable for re-use. If the leases are set too short, however, this can be annoying and create extra load for the server as it must constantly lease out new IPs. You also need to keep tabs on IP utilization, so you can determine whether you are under- or over-utilizing the IP addresses you have available.

Some of the metrics you can examine for DHCP server performance include how fast the server is processing requests, how many requests end up in a queue, and the number of packets expiring while requests are waiting. You can also look at whether any negative acknowledgment messages were sent out by the server or whether any decline messages were received.

The importance of the DHCP server shouldn’t be understated. As noted before, this is the server responsible for allocating the IP addresses on your network, and without a properly functioning DHCP server you can end up with big problems with devices communicating between one another, or even properly connecting to the network.

When you engage in regular monitoring and management of your DHCP server, you can check whether it is running as it should be. Monitoring helps you to step in quickly to fix any problems.

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DHCP Monitoring and DHCP Management Best Practices

There are several DHCP monitoring and DHCP management best practices to help ensure issues do not reach your end users.

DHCP monitoring and management best practices

  1. Regular monitoring: By keeping track of your IP addresses and DHCP server performance regularly and consistently, you’re more likely to spot issues as soon as they occur. When you have a clear baseline of DHCP server performance and behavior, a spike in activity or a sudden slowdown in performance can indicate an issue. If you see this on your monitoring reports, you will be able to fix this issue quickly.
  2. Auditing and assessment: Another good move is to go through regular auditing and assessment processes to ensure your DHCP monitoring practices are functioning correctly. Look at what problems your monitoring process uncovered and consider whether there have been any issues that could have been managed better.
  3. Reporting processes: A large part of the assessment process also includes using regular reporting. Reporting can be set up from many tools to occur on a set schedule or as-needed. Reports can show you all of the information on what messages were sent or received by the DHCP server and can also show you metrics such as uptime, network performance, and IP allocation processes.
  4. Escalation procedures: When DHCP management and IP address allocation is a big part of your business network, having a quick resolution can be critical to service delivery. Ensure you have a clear escalation procedure for issues, so if problems persist they can be fixed quickly by the right people.
  5. Use tools: Automating part of this process can take some of the pressure off IT teams. I suggest starting with a tool like SolarWinds IP Address Manager (IPAM), which can perform IP address scanning to discover and monitor all the IP addresses on your network, and can also track subnets and IP address blocks. By finding abandoned IP addresses, IPAM can help you to easily reclaim them. It also fully integrates your IP address management with DNS and DHCP server management, so you can keep track of everything in one centralized console. This can save you time and energy and prevent you from needing to switch between different tools. It has the ability to monitor Microsoft, Cisco, and ISC DHCP servers.
    Alternatively, SolarWinds offers Engineer’s Toolset which includes tools for monitoring IP addresses and DHCP servers, such as a Subnet Calculator, DHCP Scope Monitor, DNS Structure Analyzer, and DNS Audit tool. For example, the Scope Monitor can poll DHCP servers to determine which scopes are low on IP addresses, so more can be allocated.

There are several different monitoring tools on the market to help you with DHCP management processes, so check them out and find ones that work for you. Many of these tools also offer free trials so you can test them before you roll them out to your entire business network. Try all of IPAM’s or Engineer Toolset’s features for free for 30 days.

Get Started with DHCP By Using the Right Tools

The importance of DHCP for the functioning of your network shouldn’t be underestimated—when something goes wrong, it can go really wrong. While DHCP management sounds daunting, remember, the reality is, with the help of a few tools you can easily keep this process under control. Follow the best practices above and invest in a tool like SolarWinds IP Address Manager. With the right product in hand, you’ll be able to easily keep your DHCP servers configured correctly and spot any issues before they affect your end users.

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