All about Domain Name Server (DNS)

What is DNS What is DNS What is DNS

Introduction to Internet Protocols

One of the most used internet protocols is the Domain Name Servers known also as DNS. An internet protocol is represented by the computer networking model and usually is a communication protocol used on the web worldwide. Known also as TCP/IP protocols because TCP is related to Transmission Control Protocol and IP to Internet Protocol. These two protocols were also the first protocols created.

Both Transmission Control Protocol and Internet Protocol offer data communication showing how data should be transmitted, addressed, routed, packetized and received. The TCP and the IP model together with other protocols are maintained by Internet Engineering Task Force knew also as IETF. 8 steps on how to move your website to a new web hosting provider.

There are multiple layers of protocol suites and each of it contains specific protocols:

  1. Application layer which contains BGP, DHCP, FTP (File Transfer Protocol), DNS (Domain Name server), IMAP (for email purposes), LDAP, MGCP, NNTP, NTP, POP, ONC, RPC, RTP, RIP, SIP, RTSP, SMTP (also for email purposes), SNMP, SSH, Telnet and so on.
  2. Transport layer has protocols such as TCP, UDP, DCCP, and SCTP and so on.
  3. Internet layer has a few protocols like IPv4, IPv6 which together are making the Internet Protocol, ICMP, ECN, and others.
  4. Link layer with ARP, NDP, PPP, OSPF and more.

Introduction to Domain Name server

The Domain Name server (DNS) is an internet protocol used for naming computers, servers, services or any other types of servers connected either to Internet or Intranet which represent a website.  If you do not use Domain Name server, you website will be available via an IP address which contains multiple numbers and dots. The DNS contains a lot of information such as the name of DNS, the extension after you can see either the country or the purpose of the domain name server. Additionally, the DNS offers information about the registrant of the domain such as name, address, and contact details together with the expiration date if it is the case.

The most usual types of records available in DNS database is represented either by DNS zone authority (SOA), SMTP mail exchangers (MX), IP Addresses (A and AAAA), name servers (NS), domain name aliases (CNAME) and pointers for reverse DNS lookups (PTR).

How Domain Name server works

When you think about DNS, you should think about a phone book which converts host names of computers in IP address so if you have the domain name www.yoursite.com, it will convert to 93.184.216.119 for IPv4. However, the Domain Name server is faster than a phone book because it is automatically updating without affecting the visitors of the domain name.

With Domain Name server you also have available cloud services and content delivery networks such as Cloud Flare helping you to back up your website and offering the backed up version in case your live one is down due to technical issues.

DNS also offers administrative partitioning such as public suffixes.

Usage of Domain Name server

In nowadays everyone uses the internet so you use the Domain Name server without knowing every day since you have The Internet on your computer, laptop, and smartphone or on another device. You do not need a specific internet browser, devices, software or operating server in order to use Domain Name server. You can use either Window, Mac, Linux, Android or Firefox, Dolphin, Edge, Internet Explorer, Chrome, Safari in order to access a website and its related service.

Domain Name server is used when:

  • You access a website giving the name the website already has together with its extension like yourwebsite.com.
  • You access the FTP (File Transfer Protocol) of a website and usually writing in the hostname ftp.domain.com.
  • You access a page of the website such as yourwebsite.com/about.
  • You access your email client and you need the hostname like smtp.yourwebsite.com.
  • You have an email address such as This email address is being protected from spambots. You need JavaScript enabled to view it..
  • You access a subdomain of a domain like example.yourwebsite.com.
  • You access a gaming server, chat server or any kind of services related to a website.

If you see, you can tell that the Domain Name server protocol is working close with other Internet protocols such as IP, FTP, and SMTP which are usually used by web designers, web programmers, SEO consultants, hardware experts or just simple persons.

Basic information about Domain Name server

The Domain name space is actually a tree data structure having each node or leaf associated with an information regarding the domain name. If we take for example www.domain.com, the label yourwebsite specifies a subdomain of the com domain while the www is a subdomain of yourwebsite.com. The tree data structure may have almost 127 levels with multiple labels which some of them may contain zero to 63 characters.

DNS has a specific message format which uses queries and replies. Each message has a header and four sections: authority, question, answer, and an additional space. The header is the controller of those sections. In the header section you can find various fields like a number of authority resource records, the number of additional resource records, the number of questions, and the number of answers, flags and identification. There are multiple resource record fields (RR) like:

  • NAME which actually contains the name of the node to which the record pertains and its length is variable.
  • TYPE is containing the type of resource record in numeric format and usually, its length is 2 octets.
  • CLASS contains the class code and it also has a length of 2 octets.
  • TTL is counting the seconds of resource record being valid and it has a length of 4 octets
  • RDLENGTH is representing the length of RDATA field which has 2 octets.
  • RDATA is the additional resource record specific data and it has a variable length.

DNS also uses UDP (User Datagram Protocol) and the port 53 in order to transport requests. When the response data size exceeds 512 bytes, DNS uses automatically TCP (Transmission Control Protocol).

Domain Name server tools

On the Internet, there are available multiple tools used by simple people, Internet Service Providers, Police or detectives. Some of them are:

  • DNS report: which helps you to find email and DNS issues. You just need to enter a zone name like website.com and you will receive a detailed report with results. Some of them maybe red meaning a fail result, other ones may be orange so they are warning results while other are green and they pass the check and there might be some gray ones which are actually info results. This report is testing the written domain name server with multiple tests such as parent zone provides NS records, the number of nameservers, unique nameserver IPs, all name servers respond, open DNS servers, all nameservers authoritative, TCP allowed and so on. There are more than 40 tests. This tool is available at http://www.dnsstuff.com/
  • WHOIS Lookup is an important tool, also available at DNS Stuff website where you need to enter either a domain name or an IP address. Once you entered the website you can see the created date, updated date and the WHOIS server of the website. Additionally, you can see the registrar, the contact information, and the nameservers together with the IPs. You can also see the detailed WHOIS response if you need it.
  • Trace Route is another way to find the path to your host. This service is available at DNS Stuff and you need to write an IP address then you need to press the white right arrow on a blue background. Now you can see a table with the traceroute results for the specific IP you have entered. You can see the ICMP, UDP, TCP, IP, hostname, country and time together with the operating server and a map.
  • DNS Speed Test is a tool available at https://www.ultratools.com/ which helps you to see the performance of a Domain Name server. You need to write the domain name or a hostname and to press the Go button. Next, you will see a similar table with the one from the Trace Route tool, but it contains other information such as performance information for each level. In this table, you can see the name servers, the minimum, maximum and average time in milliseconds  for each name server regarding AAAA, CNAME, MX, SOA, A , SPF, SRV, and TXT. Additionally, there are available other tables below this one with information regarding TLD servers and Root servers together with the minimum time, maximum time and average time.
  • The DNS Query Estimator is a precious tool which helps you to estimate the volume of DNS queries to your domain name per month. However this tools is new and it is not available yet on ultratools.com.
  • DNS Traversal Tool is available on utratools.com and it helps you to verify that all the DNS servers contain the same data. You can also see if the DNS servers have propagated to all their nameservers. There are also available information like the extension and the IP for each subdomain.
  • The DNS Zone Transfer Lookup is an advanced Lookup tool which provides you with zone transfer and DNS information. You need to enter either a host name or a domain name, but you might get an error if the zone does not allow transfers.
  • Ping Host is a basic and one of the most popular DNS tools which help you to ping a domain name. You can do this through the website: http://www.webdnstools.com where under the Ping Host field you should write a hostname and then press the Ping button. You will see a report where you ping the written hostname with 64 bytes from and in the end you can see how many packets you transmitted, received and how many percentages of the packets are lost. Also, you can see the time need to do this operation. You can also ping a domain name using your computer and in Windows opening the Command Prompt where you write ping example.com and then press enter.
  • IP Calculators is a suite of tools regarding IP addresses, most of them are converters. You can use them at http://www.webdnstools.com. I remind some of them: Subnet Address, What’s My IP Address, IP Address to an integer, IP address from integer, IP Address Country, CIDR to IP Address Range, Compress IPv6, and Expand IPv6 Address.
  • ISP Cached DNS Lookup is available at http://dnstools.fastnext.com/ together with other tools I will mention later. This one is checking the cached version of a DNS at major Internet Service Providers. You just need to enter a domain name and to press the Lookup button near the tool. You will see a table where countries, servers, and answers of multiple Internet Service Providers.
  • Spam Database Lookup is used to see if your mail server related with your DNS is in any spam database. You write the hostname and you will see a table with multiple databases and if you see a green ball near them than the written hostname is not listed, for red ones you must know that you are listed while for blue ones there is a timeout error and for gray ones you should know that the spam databases are offline. This tool is available at http://dnstools.fastnext.com/ also like the previous one.
  • IP Information offers you data regarding an IP including its location and it is similar to What’s My IP Address.
  • The Decimal IPs tool is an actually a calculator which converts a decimal IP into a regular one and back.
  • With IP History, you can see the history of a domain regarding IPs. This interesting tool is available at http://viewdns.info/. You just enter the domain name and you wait for a little until the table is loaded. Once the table is loaded you can see the IP addresses, the locations, IP address owners and the date when the domain name was last seen on the specific IP.
  • The Reverse WHOIS Lookup is a new tool also available at http://viewdns.info/ where you can find a domain name by entering the registrant name or email address while the Reverse IP Lookup from the same website offers you the possibility to find all sites hosted on a given server so you just need to write either the domain or the IP of the server. There is also available a tool like Reverse NS Lookup where you can find all the sites which use a given nameserver. You can find the reverse DNS entry for an IP address using the Reverse DNS Lookup.
  • With Is, My Site Down you can see if a website is down or not by entering a domain name. A similar service is also provided by WordPress if you use the Jetpack plugin for WordPress websites. In this second case, you will receive an email when your website is down and when it is up again.
  • To test for Firewall issues regarding China and Iran you can use the Chinese Firewall test and the Iran Firewall Test. In this case, you will know if your website is accessible from one or both of the specific country.
  • The Get HTTP headers from http://viewdns.info/ are used to view the headers returned by a domain name while the port scanner checks if ports are opened on a server.
  • At http://viewdns.info/, you can also use Google Pagerank Checker which usually shows a website popularity and authority on the Internet offering vital information for an SEO Master.
  • You can always convert a URL with special symbols to a regular and more readable format with the URL/ String Decode.
  • http://viewdns.info offers you the possibility to determine if a domain name provides or not free email addresses by writing the domain like yahoo.com.
  • If you want to contact the abuse authority of a domain name but you do not know where to find its contacts you can always use Abuse Contact Lookup and with MAC address Lookup you can determine the manufacturer of a network device.
  • Other tools that you can use are the ASN Lookup which offers you information Autonomous server Number and DNSSEC Test for domains. Both are available at http://viewdns.info.
  • Special suggestion tools finding the best domain name for yourself and for your loved ones are also available. I mention just a part of them: Lean Domain Search available at http://www.leandomainsearch.com offers you thousands of suggestion related to your keyword. Nameboy tool from http://www.nameboy.com automatically offers suggestions using city name and describing keyword. Name Mesh gives you multiple SEO advice together with a good suggestion for your domain name. With Name Tumbler, you can combine a keyword together with adjectives, animals, places, buildings, and multiple suffixes together with special extensions such as .asia, .ws and so on. Domain Puzzler offers suggestions together with multiple extensions like .uk, .net, .eu, .me, .biz and so on. And one of the most interesting ones is Wordoid which helps you to create high, medium and low-quality words in French, English, German, Italian and Spanish. You can use an ending predefined word combined with yours.

Installing and optimizing DNS

You can use an old operating server such as Windows 2000 DNS or something newer like Windows NT 4.0 DNS. For both, the process is the same. To install DNS you need to click start and then to go to settings and at Control panel. Here you just click twice Add/Remove Programs and then at Windows Components you select Networking Services and click on Details. In subcomponents of Networking Services, you need to check the Domain Name server box and to click OK and Next. In copy files from, type or browse the path for Windows distribution files and then just click ok.

To create a forward lookup zone you should go to Start and then at Programs. Here go to Administrative Tools and at DNS, you should expand the server and right click the Forward Lookup Zone folder in order to choose New Zone. Click next when the wizard appears and ensures that the Standard Primary and the Forward Lookup Zone are selected and go to the next phase. At the page with New Zone type the name of your zone and click next. Select create a new file with this file name and click next once and then finish.

In order to create a reverse lookup zone, you need also to expand the DNS server and to right click your server. Now choose New zone click continue and follow the steps for the previous operation. Additionally, you need to ensure that network ID is selected and you need to write the network ID. Select create a new file with this file name and again click next once and finish in the end.

How to flush your Domain Name server

One of the most used operations regarding Domain Name server are the ping one and the flush one. I already mentioned about ping tools above together with a method to make your own ping test using your computer.

To flush a DNS you can use Windows, open the command prompt by going at the start and then at run where you type cmd and OK. Once opened the command prompt you need to enter the proper command.  Use the IP config /flushdns command and press enter. You will see the following messages: “Windows IP Configuration” on the first line and in the second one “Successfully flushed the DNS Resolver Cache”.

If you have an MAC OS x you need to go to a terminal and write the following command for 10.5 and newer versions dscacheutil –flushcache in order to flush DNS and then sudo killall –HUP mDNSResponder to reload it. However for older versions than 10.4 you need to enter lookup –flushcache and then the reload command. In both cases, you will be prompted for a password so you should know the administrator password.

If you use Linux you also need to open the terminal as root and then to restart the network-manager so write service network-manager restart and press enter.

Last modified onThursday, 19 May 2016 20:48
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