Smart Bro DNS vs. Google Public DNS

Here is a study comparing the DNS server from Smart Bro performance against that of Google Public DNS.

It has been thought that because Google has a large database that using their public DNS server would increase internet speed. So how true is it?

To begin, let me illustrate what happens when we browse the internet. At least as I understood it.

It starts from our computer. When we open our browser and type in a URL in the address bar called host name (like www.google.com), our computer sends out this information to the internet. But every machine, including the servers that host a domain, do not have word names, it has numeric names called IP address (like 173.194.38.144). The words are only for humans because we are better at remembering words than numbers.

To resolve this, another server is needed to translate the host name into an IP address before your request for a web page can continue. That is the job of a DNS server, to resolve host names into its equivalent IP address then directs you to the proper server.

Your computer sends out request to a host name, host name gets translated into an IP address by a DNS server, target IP address sends out requested data to your computer.

Smart Bro vs. Google Public DNS
To compare the two let us take the latency by using the ping command to check for delay but according to Google the delay in internet browsing also includes the host name resolution time.

"In addition to the ping time, you also need to consider the average time to resolve a name. For example, if your ISP has a ping time of 20 ms, but a mean name resolution time of 500 ms, the overall average response time is 520 ms. If Google Public DNS has a ping time of 300 ms, but resolves many names in 1 ms, the overall average response time is 301 ms.

The formula then for delay is:

Delay = connection latency + host name resolution time

To get the host name resolution time, I used the nslookup command in a batch file in DOS. I have taken some data at different times of the day as internet traffic varies during the day. Here is a summary of the result.

Time	Host Name	Ping Result		DNS Server Resolution Time		Total Delay
		Smart Bro	Google Public DNS	Smart Bro	Google Public DNS	Smart Bro	Google Public DNS
Day1 @ 1am	www.google.com	312 ms	479 ms	1110 ms	1130 ms	1422 ms	1609 ms
	www.facebook.com	447 ms	290 ms	1140 ms	1050 ms	1587 ms	1340 ms
	cyberliving.blogspot.com	518 ms	446 ms	1160 ms	2170 ms	1678 ms	2616 ms
Day1 @ 9am	www.google.com	331 ms	512 ms	1290 ms	1120 ms	1621 ms	1632 ms
	www.facebook.com	433 ms	474 ms	1080 ms	1140 ms	1513 ms	1614 ms
	cyberliving.blogspot.com	486 ms	507 ms	1380 ms	1130 ms	1866 ms	1637 ms
Day1 @ 4pm	www.google.com	411 ms	318 ms	1020 ms	700 ms	1431 ms	1018 ms
	www.facebook.com	358 ms	283 ms	880 ms	640 ms	1238 ms	923 ms
	cyberliving.blogspot.com	420 ms	303 ms	1090 ms	700 ms	1510 ms	1003 ms
Day1 @ 9pm	www.google.com	509 ms	438 ms	1140 ms	900 ms	1649 ms	1338 ms
	www.facebook.com	399 ms	330 ms	1020 ms	870 ms	1419 ms	1200 ms
	cyberliving.blogspot.com	510 ms	447 ms	6390 ms	940 ms	6900 ms	1387 ms
Day2 @ 12am	www.google.com	344 ms	298 ms	700 ms	550 ms	1044 ms	848 ms
	www.facebook.com	288 ms	255 ms	710 ms	430 ms	998 ms	685 ms
	cyberliving.blogspot.com	302 ms	325 ms	670 ms	640 ms	972 ms	965 ms
Day2 @ 10am	www.google.com	645 ms	349 ms	1670 ms	750 ms	2315 ms	1099 ms
	www.facebook.com	505 ms	288 ms	1450 ms	720 ms	1955 ms	1008 ms
	cyberliving.blogspot.com	566 ms	300 ms	1650 ms	720 ms	2216 ms	1020 ms
Day2 @ 7pm	www.google.com	378 ms	330 ms	840 ms	570 ms	1218 ms	900 ms
	www.facebook.com	428 ms	303 ms	740 ms	560 ms	1139 ms	863 ms
	cyberliving.blogspot.com	305 ms	349 ms	810 ms	820 ms	1115 ms	1169 ms

​
Comparing the two, in general, using Google Public DNS gives a latency and host name resolution that is lower, thus the overall delay is much lower compared to that of my ISP.

It is interesting to note though that my first two results in Day 1 is showing a better performance for my ISP. And this is during a non-peak hours my time. But otherwise, Google Public DNS is thus far winning the battle. That is, of course, only one part of the problem solved. We have only looked at the delay from the moment our computer made the request until we got a response.

What does it mean to you? When you go to a certain web page, your computer actually makes several http requests. This is because web pages have javascript, CSS, html, images, Flash, etc. which are separate files in themselves saved at the same domain or from other domains and each one requires a separate request (http request) to the same domain.

Here is an example:
If I would have visited www.facebook.com on Day1 @ 9pm and it requires a total of 5 http requests, using my ISP's DNS would have a delay of 7.095s (5*1419ms) while with Google Public DNS it would only be 6s (5*1200ms) or a difference of approximately 1 second. With higher http request for a page the longer you will have to wait and the bigger difference between the two.

Throughput Speeds
How about the download and upload speed (Throughput) of our internet connection? Does using other DNS server improve it? For this, I have to use the online testing tool at speedtest.net. I choose three locations to test my download and upload speed. One nearest my location, one midway between my location and the Americas and one in the United States.

Time	Down/Up Speed	Tarlac		Lutsk		Sioux Falls SD
		Smart Bro	Google Public DNS	Smart Bro	Google Public DNS	Smart Bro	Google Public DNS
Day1 @ 10am	Download Speed	0.35Mbps	0.25Mbps	0.40Mbps	0.30Mbps	0.53Mbps	0.43Mbps
	Upload Speed	0.15Mbps	0.15Mbps	0.21Mbps	0.17Mbps	0.23Mbps	0.17Mbps
Day1 @ 4pm	Download Speed	0.46Mbps	0.55Mbps	0.77Mbps	0.71Mbps	0.32Mbps	0.71Mbps
	Upload Speed	0.16Mbps	0.18Mbps	0.23Mbps	0.20Mbps	0.17Mbps	0.29Mbps
Day2 @ 12am	Download Speed	0.94Mbps	0.34Mbps	1.03Mbps	0.30Mbps	1.11Mbps	0.48Mbps
	Upload Speed	0.15Mbps	0.13Mbps	0.25Mbps	0.18Mbps	0.29Mbps	0.29Mbps
Day2 @ 10am	Download Speed	0.20Mbps	0.43Mbps	0.53Mbps	0.46Mbps	0.36Mbps	0.48Mbps
	Upload Speed	0.14Mbps	0.15Mbps	0.20Mbps	0.21Mbps	0.26Mbps	0.27Mbps

The result above is now reversed. This time, it looked like Google has lower download and upload speeds compared to Smart Bro.

If I am to translate this into browsing speed, it will be like this. It is thought of that currently, the average size of a page is 1.3MB. Let us say I wanted to visit a site (www.exampleLutsk.com) located in the area of Lutsk, Ukrain during the time Day1 @ 10am, it would take me to download the content of the page (1.3MB) in 26 seconds (0.4Mbps=0.05MBps) using my ISP's DNS while with Google it would be 30.5 (0.3MBps=0.0375MBps) seconds or a difference of 4 seconds between the two.

Summary
With the tabulated results above, I could say that there is no difference with using my Smart Bro's DNS against that of Google Public DNS in terms of internet browsing speed. That is because, whatever advantage Google had with latency and host name resolution was erased by the download and upload speed. One reason I see that caused the bandwidth reduction in using Google's Public DNS is that it could be redirecting me to a server further from my location. But this is something that I have not verified and is beyond the scope of this post.

Increased HTTP look-up or not, notice at the tabulated ping results that my round trip time (RTT) is quite large. If some believe that an RTT below 100ms is what is deemed good/acceptable couple that with an average of 0.58Mbps (only results using Smart Bro DNS was used in the calculation) when it is rated at 3Mbps then what I have is mediocre at best.

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