Linux Local DNS caching using dnsmasq
Source: http://www.webupd8.org/2009/12/faster-browsing-in-linux-with-local-dns.html
Source: http://www.webupd8.org/2009/12/faster-browsing-in-linux-with-local-dns.html
FASTER BROWSING IN LINUX WITH LOCAL DNS CACHE
A local DNS cache can help for faster browsing since you’re caching the DNS request instead of attempting that request multiple times. The internet speed will not get any faster, but the browsing speed will improve, because on each website there are usually quite a few DNS requests for which the local DNS cache will be used, bringing the query time to almost 0. You can find more info about DNS, on Wikipedia.
To see how fast your current domain name servers (DNS) are, open a terminal and paste this:
(Or dig google.com or whatever domain)
You should see something like this:
Notice the "Query time" in bold. It's usually somewhere near 50 msec. (it depends on your domain name servers).
Run this one more time. If the query time decreases to less than 5 msec, it means your internet service provider DNS already uses some caching method and you do not need to follow this how-to. If the response time is almost the same and you are using a cable (broadband) internet connection, you can use this guide to cache the DNS for faster internet browsing.
Firstly, I would like to thank embraceubuntu for this how-to, I've just made it more newbie-friendly. So the credits go to him.
Before we get started, please note that there is an easier method on doing this (by only installing (well, actually you need to edit /etc/bind/named.conf.options with your ISP DNS) resolvconf and bind9: sudo apt-get install resolvconf bind9) but in my tests, using resolvconf and bind9, the first DNS query time was 200-300 msec (maybe it needs some tweaking but I couldn't figure out why there is such a big query time the first time) and then since it was cached, it went to 0. But the method I am going to explain will get an initial query time equal to your default DNS (~50 msec for me, as opposed to 200-300 msec which I got by using resolvconf and bind9).
Let's get started!
To see how fast your current domain name servers (DNS) are, open a terminal and paste this:
dig yahoo.com(Or dig google.com or whatever domain)
You should see something like this:
; <<>> DiG 9.6.1-P1 <<>> yahoo.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42045
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;yahoo.com. IN A
;; ANSWER SECTION:
yahoo.com. 20142 IN A 69.147.114.224
yahoo.com. 20142 IN A 209.131.36.159
yahoo.com. 20142 IN A 209.191.93.53
;; Query time: 50 msec
;; SERVER: 208.67.220.220#53(208.67.220.220)
;; WHEN: Wed Dec 9 13:21:48 2009
;; MSG SIZE rcvd: 75Notice the "Query time" in bold. It's usually somewhere near 50 msec. (it depends on your domain name servers).
Run this one more time. If the query time decreases to less than 5 msec, it means your internet service provider DNS already uses some caching method and you do not need to follow this how-to. If the response time is almost the same and you are using a cable (broadband) internet connection, you can use this guide to cache the DNS for faster internet browsing.
Firstly, I would like to thank embraceubuntu for this how-to, I've just made it more newbie-friendly. So the credits go to him.
Before we get started, please note that there is an easier method on doing this (by only installing (well, actually you need to edit /etc/bind/named.conf.options with your ISP DNS) resolvconf and bind9: sudo apt-get install resolvconf bind9) but in my tests, using resolvconf and bind9, the first DNS query time was 200-300 msec (maybe it needs some tweaking but I couldn't figure out why there is such a big query time the first time) and then since it was cached, it went to 0. But the method I am going to explain will get an initial query time equal to your default DNS (~50 msec for me, as opposed to 200-300 msec which I got by using resolvconf and bind9).
Let's get started!
Manually configuring the local DNS cache
1. Install DNSMasq:
2. Configure dnsmasq.conf
Press Alt + F2 and type:
Now search for "listen-address" (it's on line 90 on my Ubuntu Karmic installation), remove the "#" character in front of "listen-address" and add "127.0.0.1" after the "=" (all without the quotes). Basically, this is how the "listen-address" line should look like after editing it:
(Optional) You can also edit the cache size if you want. Search for this in the same file: "#cache-size=150" (it's on line 432 on my Ubuntu Karmic installation), remove the "#" character in front of the line (this uncomments it) and change "150" with the size you want for you DNS cache. This is how the line should look after editing it:
Obviously, "500" can be any number you want.
Don't forget to save the changes!
3. Edit dhclient.conf
Press Alt + F2 and type:
For newer Ubuntu versions (tested on Oneiric), dhclient.conf has moved, so use the following command instead:
And modify the "prepend domain-name-servers" (it's on line 20 on my computer) to look like this:
4. Edit resolv.conf
Press Alt + F2 and paste this:
Initially, this is how the resolv.conf file looks like:
Where ISP_DNS1 and ISP_DNS2 are your ISP domain name servers (or 8.8.4.4, etc if you are using Google DNS and so on).
Put this as the first line in your resolv.conf file:
Which means this is how your resolv.conf file will look like:
Again, ISP_DNS1 and ISP_DNS2 are your ISP domain name servers.
As an example, this is how my resolv.conf file looks like (using local DNS cache, a Google DNS and an OpenDNS DNS):
4.1 If you are using a DSL connection, you need to make sure the ppp client will not overwrite your /etc/resolv.conf file. To do this, press Alt + F2, and paste this:
Search for "usepeerdns" and replace it with "#usepeerdns" (we used "#" to comment that line so it's ignored).
5. Restart your networking and dnsmasq:
-Networking:
-DNS:
Please note that you can use this last command at any time you want to restart your DNS cache (flush DNS, clear the cache - call it whatever you want) without restarting the computer.
6. Testing
To see the peformance improvement, open a terminal and type:
The first time, it should be the same like in the beginning of the post (~50 msec. for me). Now type it again! You should see something like this:
0 msec. query time, because the domains are now cached.
Note: Using the method above, the DNS cache will be cleared once you reboot your computer. For persistent DNS caching (on the hard disk), see this excellent how-to on Ubuntu Forums.
sudo apt-get install dnsmasq2. Configure dnsmasq.conf
Press Alt + F2 and type:
gksu gedit /etc/dnsmasq.confNow search for "listen-address" (it's on line 90 on my Ubuntu Karmic installation), remove the "#" character in front of "listen-address" and add "127.0.0.1" after the "=" (all without the quotes). Basically, this is how the "listen-address" line should look like after editing it:
listen-address=127.0.0.1(Optional) You can also edit the cache size if you want. Search for this in the same file: "#cache-size=150" (it's on line 432 on my Ubuntu Karmic installation), remove the "#" character in front of the line (this uncomments it) and change "150" with the size you want for you DNS cache. This is how the line should look after editing it:
cache-size=500Obviously, "500" can be any number you want.
Don't forget to save the changes!
3. Edit dhclient.conf
Press Alt + F2 and type:
gksu gedit /etc/dhcp3/dhclient.confFor newer Ubuntu versions (tested on Oneiric), dhclient.conf has moved, so use the following command instead:
gksu gedit /etc/dhcp/dhclient.confAnd modify the "prepend domain-name-servers" (it's on line 20 on my computer) to look like this:
prepend domain-name-servers 127.0.0.1;4. Edit resolv.conf
Press Alt + F2 and paste this:
gksu gedit /etc/resolv.confInitially, this is how the resolv.conf file looks like:
nameserver ISP_DNS1
nameserver ISP_DNS2Where ISP_DNS1 and ISP_DNS2 are your ISP domain name servers (or 8.8.4.4, etc if you are using Google DNS and so on).
Put this as the first line in your resolv.conf file:
nameserver 127.0.0.1Which means this is how your resolv.conf file will look like:
nameserver 127.0.0.1
nameserver ISP_DNS1
nameserver ISP_DNS2Again, ISP_DNS1 and ISP_DNS2 are your ISP domain name servers.
As an example, this is how my resolv.conf file looks like (using local DNS cache, a Google DNS and an OpenDNS DNS):
nameserver 127.0.0.1
nameserver 8.8.4.4
nameserver 208.67.220.2204.1 If you are using a DSL connection, you need to make sure the ppp client will not overwrite your /etc/resolv.conf file. To do this, press Alt + F2, and paste this:
gksu gedit /etc/ppp/peers/providerSearch for "usepeerdns" and replace it with "#usepeerdns" (we used "#" to comment that line so it's ignored).
5. Restart your networking and dnsmasq:
-Networking:
sudo /etc/init.d/networking restart
-DNS:
sudo /etc/init.d/dnsmasq restartPlease note that you can use this last command at any time you want to restart your DNS cache (flush DNS, clear the cache - call it whatever you want) without restarting the computer.
6. Testing
To see the peformance improvement, open a terminal and type:
dig yahoo.comThe first time, it should be the same like in the beginning of the post (~50 msec. for me). Now type it again! You should see something like this:
dig yahoo.com
; <<>> DiG 9.6.1-P2 <<>> yahoo.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57501
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;yahoo.com. IN A
;; ANSWER SECTION:
yahoo.com. 20982 IN A 209.131.36.159
yahoo.com. 20982 IN A 69.147.114.224
yahoo.com. 20982 IN A 209.191.93.53
;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed Dec 9 14:43:41 2009
;; MSG SIZE rcvd: 75
0 msec. query time, because the domains are now cached.
Note: Using the method above, the DNS cache will be cleared once you reboot your computer. For persistent DNS caching (on the hard disk), see this excellent how-to on Ubuntu Forums.
Great site for these post and i am seeing the most of contents have useful for my Carrier. Thanks to such a useful information.Any information are commands like to share him.
ReplyDeleteInformatica training in chennai
Your thinking toward the respective issue is awesome also the idea behind the blog is very interesting which would bring a new evolution in respective field. Keep update more information.
ReplyDeleteArchitectural Firms in Chennai
Architects in Chennai
ReplyDeleteIts very useful to me. Wonderful blog.. Thanks for sharing informative Post.
Installment loans
Payday loans
Title loans
This comment has been removed by the author.
ReplyDeleteExcellent and very cool idea and the subject at the top of magnificence and I am happy to this post..Interesting post! Thanks for writing it. What's wrong with this kind of post exactly? It follows your previous guideline for post length as well as clarity..
ReplyDeleteSoftware Testing Training in Chennai
SEO Training in Chennai
Informatica Training in Chennai
Digital Marketing Training in Chennai
Very nice post here and thanks for it .I always like and such a super contents of these post.Excellent and very cool idea and great content of different kinds of the valuable information's.
ReplyDeletebest rpa training in bangalore
rpa training in bangalore | rpa course in bangalore
RPA training in bangalore
rpa training in chennai
rpa online training
Awesome..You have clearly explained …Its very useful for me to know about new things..Keep on blogging..
ReplyDeleteAWS Training in Bangalore
AWS Training in pune
Attend The Python training in bangalore From ExcelR. Practical Python training in bangalore Sessions With Assured Placement Support From Experienced Faculty. ExcelR Offers The Python training in bangalore.
ReplyDeletepython training in bangalore
Thank you for allowing me to read it,It is very useful for me. And thanks for sharing the nice article, keep posting or updating new article!!
ReplyDeleteMachine Learning Course
I truly like your style of blogging. I added it to my preferred's blog webpage list and will return soon…
ReplyDeletePMP
Stunning! Such an astonishing and supportive post this is. I incredibly love it. It's so acceptable thus wonderful. I am simply astounded.
ReplyDeletedifference between analysis and analytics
I am another customer of this site so here I saw various articles and posts posted by this site,I curious more energy for some of them trust you will give more information further.
ReplyDeletetraining provider in malaysia
Python Training in Bangalore
ReplyDeletePython Classes in Bangalore
Mindblowing blog very useful thanks
ReplyDeleteSEO Training in Velachery
SEO Training in Chennai
WPC 2029
ReplyDeleteteam everyone working as per the working plan. Machine Learning Course in bangalore
ReplyDeleteThanks for sharing such an wonderful and informative blog.
ReplyDeleteLinux training in Pune