Category Archives: Servers

Basic review of the DHCP server.

DHCP server helps networks administrators and makes their work lighter!

Networks have become really complex. The amount of devices asking for connection has grown massively. Therefore, the administration and maintenance of networks’ resources are really demanding. 

What is DHCP?

DHCP is a network management protocol that automates the necessary configuration for devices to connect and communicate on IP networks. Without this configuration, devices can’t access network services like NTP or DNS. They can’t establish any communication based on TCP or UDP. DHCP means Dynamic Host Configuration Protocol. 

A DHCP server can automatically provide an IP address, default gateway address, the subnet mask, DNS settings, and other important network configuration information necessary for devices to connect and talk with other endpoints. 

DHCP architecture’s elements.

By knowing DHCP elements and their functions, you can better approach the way DHCP works.

  1. DHCP server.

It’s a machine, server, router, or whatever acting as host, with the DHCP enabled. It has the IP addresses and all the configuration information. It’s responsible for responding to IP addresses queries, supplying available IP addresses, storing them during the time their lease allows and renewing them when that time expires. It manages the communication with client devices.

  1. DHCP client.

It’s the endpoint or device asking for a connection. Therefore, it’s who gets the IP address and the rest of the configuration information from the DHCP server. A DHCP client can be a laptop, smartphone, tablet, IoT, etc. Currently, most devices are configured to get DHCP information by default.

  1. IP address pool or scope.

It’s the range of available IP addresses the DHCP server can supply to DHCP clients. 

  1. Lease.

It establishes the time a DHCP client can keep an IP address and the rest of the information. Once the lease expires, the IP address and its data must be renewed.

  1. Subnet.

For better management, networks are partitioned into pieces called subnets.

  1. DHCP relay.

It’s an agent (router or host) used to centralize DHCP servers, not to have a server on every subnet. This agent listens to clients’ messages broadcasted on the network and sends them to the configured server. This last will respond to the relay agent, which will pass the responses to the clients.

Advantages of a DHCP server.

  • It makes networks management easier while automating different tasks. 
  • It reduces the chances of human errors, like typos. IP configuration must be very accurate not have failures. When tasks are done manually, it’s easy to mistake a number, a dot, etc., while typing sequences of numbers like 102.112.135.1
  • It minimizes IP addresses conflicts. As it’s known, every device needs a unique IP address to get connected. If an IP address is duplicated, meaning assigned to two different devices, this will create a conflict. One or even both devices won’t get a connection.
  • Changes on the network can be executed without pain. If you need to change the IP address scope, addresses, endpoints, etc., you just have to configure the DHCP server, and changes will propagate to all new endpoints.

The disadvantage of a DHCP server.

DHCP protocol involves security risks. In order to make agile the process for clients joining the network fast, it doesn’t ask for authentication. This is clearly a possible entrance for malicious actors. 

Conclusion.

DHCP is a great teammate for efficiently managing networks. Knowing its details, you can use it smartly, taking the most out of it! 

Recursive DNS server – definition

The DNS infrastructure is really helping the experience of Internet surfing pleasant and easy. One of the main responsible participants is the recursive DNS server. So let’s explain a little more about it and its role in the complex DNS process.

DNS – What is it for?

The Domain Name System, or DNS for short, is a well-established method of translating domain names into IP addresses. When a user wants to visit a website, it will usually search in its browser for it. To accomplish this task, the user is going to write the domain name of the website. Unfortunately, the machines don’t understand words and names, and they work only with numbers to communicate. So in the middle is the Domain Name System, and it is solving this issue by pointing the particular domain name to its corresponding IP address.

Recursive DNS server explained.

Recursion in computing is often associated with a method of solving a particular issue. Thus, it involves a program or solution that will keep repeating itself till it reaches its goal. 

Recursive DNS servers operate between the user and the authoritative DNS servers. They perform the required searches for specific information to find an answer to the queries of the users. 

As we mentioned, the users make a request for a particular domain through a browser. Yet, the process of searching for the correct IP address is performed by a recursive DNS server. Therefore, it is important to note that they are not the holders of the database with information. They are the searchers. After the recursive DNS server finds the required IP address, it gets back to the device and provides it to the browser that requested it. Finally, the device is able to connect to the IP address, and the user reaches the website.

Globally the number of recursive DNS is significant. The most popular of them are the ones of your Internet service provider (ISP).  

The two types of lookup

The recursive DNS server performs its lookup in one of two ways. They are the following:

The first type one is considered a lot easier and quicker. This is because it contains the IP address from its cache memory. For a particular time, these servers can store the information in their cache. For what amount of time they should hold it is a decision made by the administrators. They can determine more or less time by the time-to-live (TTL) value. It is all based on the strategy of the administrators actually.

Receiving the query, the recursive DNS server is going to first search for the IP address in its cache memory. If that information is still available there and the TTL has not expired yet, the assignment is completed. It is very beneficial because the response is fast, and the recursive DNS server doesn’t need to search further in other servers.

The second type of search requires a little bit more time to be completed. It occurs in the cases when the TTL in the cache is expired. For that reason, the IP address is no longer available there. However, the recursive DNS server goes a long way to obtain the desired information. It passes through the root server, TLD (Top-Level-Domain) server, and finally to the authoritative server, which is the one able to provide the answer to the query. 

Therefore, the original goal of the recursive DNS server is only to search for information.