How to Setup DNS Caching using dnsmasq on Ubuntu

DNSmasq can be utilized to cache DNS requests for Linux distributions. nevertheless, it may be a bit difficult.

The DNS cache works to hurry up the DNS lookup that resolves an internet site’s area identify to its corresponding IP deal with. When a number of customers in your community entry the identical web site deal with, utilizing the native DNS cache server can cut back the period of time it takes to load the web.

First, let’s examine what DNS caching is.

What’s DNS Caching?

The DNS is utilized by the Web to maintain monitor of all publicly accessible on-line websites and their related IP addresses. You may examine it to a cellphone ebook. Utilizing DNS saves us from having to recollect every website’s IP deal with, which is important for the community infrastructure to speak with Web websites.

While you ask the search engine to show an internet web page, it really occurs behind the scenes.

Though your system has entry to numerous exterior DNS servers, the issue is that having a central duplicate of the DNS nonetheless accelerates transmission and backbone. That is when DNS caching comes into play.


Earlier than sending the request to the Web, the DNS cache handles identification decision for lately and continuously used domains in an effort to make the method a lot quicker.

The DNS server is accessed when essential to resolve an IP deal with to a site identify. This will put further pressure on the DNS server, particularly if the web site receives many requests on the similar time.

A DNS cache is used to scale back DNS requests and response occasions. The resolved IP addresses are saved domestically together with host information. As a substitute of initiating a brand new DNS question, the result’s retrieved from the DNS cache the following time the IP deal with or area identify must be resolved.

How does DNS caching assist resolve intermittent DNS points on Amazon EC2 Situations?

Most Linux methods don’t use an area DNS cache. Which means all DNS requests are despatched on to Amazon’s authoritative DNS resolver, which has a restrict on the variety of requests it may possibly course of at one time. DNS decision issues happen when there are lots of requests.

By implementing an area DNS cache within the system, you’ll be able to cut back CPU and community utilization whereas avoiding DNS decision errors. A neighborhood DNS cache responds to queries to exterior DNS sources resembling Amazon RDS and S3.

The DHCP protocol is used at boot time by Amazon EC2 situations related to Amazon VPCs to request a DNS server deal with.


When utilizing Amazon VPC to construct a digital personal cloud, Route 53 DNS Resolver successfully makes use of a resolver on the VPC to answer DNS requests for EC2 situations working underneath native Amazon VPC net addresses and personal entries managed zones. Resolver performs recurring lookups on public DNS servers for all further net addresses.

A DNS cache serves as a short lived document of earlier DNS queries that our system can rapidly look at whereas trying to entry a web-based web site. It retains a log of each current and subsequent session. This DNS cache makes area decision simpler and prevents errors with Amazon EC2 Linux situations.

Many customers sometimes use Amazon’s Route 53 service for DNS when accessing AWS. It is vitally simple to make use of and nearly free. However there are a selection of causes that may affect the person’s determination to make use of an area DNS server.

Whereas bind9 remains to be an important possibility for establishing an area DNS cache server, dnsmasq is way simpler to put in and configure, each on EC2 situations and on an area machine.

What’s dnsmasq?

DNSmasq is a Linux associated software that helps DNS, DHCP, TFTP and DNS caching. It’s made compact and light-weight, making it splendid for networks and firewalls with much less useful resource constraints.

It’s extremely simple to put in and configure. To arrange DNS and DHCP for subnetworks, dnsmasq is a versatile and sensible resolution.

It’s attainable to arrange this DHCP-assigned identifier and related directions for every server or for an underlying controller. Dynamic and static DHCP choices are each supported by dnsmasq. It’s moveable and might handle DNS and DHCP for no less than 1,000 purchasers.

When a DNS question is obtained, dnsmasq responds from an area cache or sends to an authoritative DNS server. Along with responding to DNS requests for addresses with a DHCP configuration, it checks the contents of the /and so on/hosts file to determine native hostnames that aren’t within the public DNS.

Utilizing the dnsmasq software as an alternative of the browser’s built-in DNS cache considerably improves Web shopping efficiency. It’s splendid for an built-in setting with restricted sources, as it is rather simple to put in and requires little or no disk area.

Options of dnsmasq

  • It’s simple to combine inside DNS servers with dnsmasq by configuring it to ship sure area identify decision queries to sure authoritative servers.
  • Server workload is diminished and reliability is elevated by utilizing the configured native DNS server.
  • DNS configuration for firewalled endpoints is sort of easy and impartial of the DNS utilized by the ISP.
  • If the port related to the Web is just not accessible whereas working a DNS verify on the pc, the lookup operation will probably be suspended instantly.
  • By PPP (Level-to-point protocol) or DHCP queries, dnsmasq can really be configured to periodically gather information instantly from the underlying area decision server.

Set up

The systemd-resolved service have to be disabled earlier than putting in and configuring the software program dnsmasq utility.

systemctl cease systemd-resolved

You can too cover it utilizing the masks attribute in order that it does not begin robotically if you reboot.

 systemctl masks systemd-resolved

Putting in dnsmasq is the primary motion after putting in it systemd-resolved. DNSmasq is preinstalled in nearly all Linux distributions. If not, you’ll be able to set up it manually. Launch a command terminal after which kind the next command to do that.

sudo apt-get set up dnsmasq

If you’re a yum person, use the next command:

sudo yum set up -y dnsmasq

This command installs and launches the utility robotically dnsmasq on the background.


After profitable set up you’ll be able to verify the standing of dnsmasq by utilizing the command under.

systemctl standing dnsmasq

If the standing exhibits “working (working)”, it signifies that the set up is full and configured on port 53. If the standing exhibits “idle (lifeless)”, you’ll want to reboot each the Ubuntu machine and dnsmasq. This can repair the error.



Dnsmasq is now able to be arrange because the native cache DNS server in your machine. The default configuration file is situated at /and so on/dnsmasq.conf. This configuration file have to be modified with a view to arrange dnsmasq utility within the system.

Use this command to open and edit the configuration file.

nano /and so on/dnsmasq.conf

The configuration file ought to solely be edited with root privileges. Simply delete every little thing within the file, together with feedback, after which copy and paste this configuration setting and reserve it.


Let me briefly describe what every of the parameters means.

  • Port – To specify or bind the port that Dnsmasq will use to obtain DNS requests.
  • area wanted – Sends solely the domains to the upstream DNS server.
  • faux personal – prevents area and port forwarding
  • listening deal with – To outline the identify server deal with. Often, the localhost is used because the default for establishing an area DNS server.
  • area – To configure the domains that dnsmasq provides to brief identifiers.
  • cache dimension – The utmost DNS cache dimension allowed within the storage.

After making all vital modifications, save and shut the configuration file. And the following step is to edit the /and so on/resolv.conf file so as to add the native host decision deal with. Use the command under to open with the nano editor.

nano /and so on/resolv.conf

Right here you will discover all of the identify servers your system makes use of for deal with decision. Additionally add the loopback deal with in that listing. Add “nameserver‘ and preserve it within the first line.

DNS resolve

Save the configuration file and shut it. For the up to date setting to take impact, restart the dnsmasq utility.

systemctl restart dnsmasq

Check native DNS cache server

It’s simple to check the native DNS server. Open a command line and use the dig command to verify for DNS caching. While you run the dig command for the primary time, the end result must be fairly generic.

└─# dig                                                                                     1 ⚙

; <<>> DiG 9.18.0-2-Debian <<>>
;; world choices: +cmd
;; Obtained reply:
;; ->>HEADER<<- opcode: QUERY, standing: NOERROR, id: 623
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

; EDNS: model: 0, flags:; udp: 512
;                 IN      A

;; ANSWER SECTION:          227     IN      A          227     IN      A

;; Question time: 31 msec
;; WHEN: Sat Oct 15 07:52:49 EDT 2022
;; MSG SIZE  rcvd: 74

Be aware that the search time is about 31 ms to get the small print of the upstream identify server. Run the identical dig command yet one more time and you may discover a big lower in search time.

└─# dig                                                                                     1 ⚙

; <<>> DiG 9.18.0-2-Debian <<>>
;; world choices: +cmd
;; Obtained reply:
;; ->>HEADER<<- opcode: QUERY, standing: NOERROR, id: 21942
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

; EDNS: model: 0, flags:; udp: 4096
;                 IN      A

;; ANSWER SECTION:          281     IN      A          281     IN      A

;; Question time: 0 msec
;; WHEN: Sat Oct 15 07:58:10 EDT 2022
;; MSG SIZE  rcvd: 74

Right here the question time is 0 msec. This is because of the truth that after working the primary question, dnsmasq saved the information, and all subsequent queries occurred instantly on account of using the saved cache. Restarting dnsmasq is important if you wish to delete the saved DNS cache.

To dam

On this article, we have now seen methods to arrange and configure dnsmasq to behave as an area DNS server. You might also be fascinated by methods to change DNS servers for quicker shopping in numerous working methods.

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