A Record

A Record ( Address Mapping Record ) is a DNS record which maps a domain name to the IPv4 address of the server which hosts the domain. An A record is used for discovering the IP address of the server connected to Internet from a given hostname. You can associate same hostname with multiple IP addresses by adding another A Record with the same hostname although with a different value of IP address.

How to check an A record

Most DNS tools let you check the A record for your website. In fact, most online tools will first show you the A record for the domain, and next show you the NS records. This checking process is calling a DNS lookup. If you have a UNIX machine you can use the “dig” command to do a DNS lookup.

Editing the A record using Plesk

Plesk has a feature-packed DNS Management tool, here you can change any of your domain records.  Setting the A record you want is simple. To edit the A record, visit the Custom DNS Records page and select the relevant domain. Next, open the drop-down menu and select “A” from the list of records. Type in the IP address that corresponds to the A record you are changing, edit the TTL to meet your requirements and click “Add New” to complete the action.

AAAA Record

The role of AAAA records is increasing in importance when it comes to converting domain names to IP addresses. In this article we discuss why AAAA is so important, and why it will likely gradually replace the A records that we all known so well as the most important DNS record. Here’s a hint: it’s all about IPv6.

A quick look at A and AAAA records

You can only really understand domain names by when you appreciate just how important the domain name system (DNS) is for the behaviour and accessibility of domain names. Domain name technologies enable users to exercise close control over their domains by using specific domain name records.

Part of this process is something called DNS resolution, the process of taking a domain name and finding the IP address that corresponds to it. This conversion process is driven by two DNS record types – the A record, and the AAAA record.

Understanding AAAA records

A and AAAA records are equally important when it comes to resolving DNS. The difference lies in that A records is used to resolve a hostname which corresponds to an IPv4 address, while AAAA records are used to resolve a domain name which corresponds to an IPv6 address.

Clearly, because IPv4 is currently the most commonly used IP address, A records are also the most commonly used in comparison to AAAA records. Yet the potential for AAAA is growing because chances are that IPv6 will be the most commonly used internet protocol address system in the future.

Advantages of using a custom AAAA record

AAAA records hold a big advantage over A records because a AAAA record can store a 128-bit IPv6 address, whereas the old A records can only store 32-bit IPv4 addresses. The internet has expanded so quickly that we are running out of IPv4 addresses, which is why IPv6 is so important. This is also why IPv4 will be replaced with IPv6 over time, and why A records will be replaced by AAAA records over time.

IPv6 addresses are stored in an AAAA record by means of hexadecimal numbers, where each four-digit segment is separated by a colon (:).

An example of an AAAA record

You can leave out a series of zeros when you specify an AAAA record, that also means that you can use the symbol “::” when there is a segment that has zeros as values. Any leading zeros are also typically omitted when specifying an IPv6 address.

Managing customer AAAA records

Plesk lets you easily manage AAAA records using the Custom DNS Records area on our hosting control panel. It is included in all our website plans and has a user-friendly interface. Creating a new record is no hassle at all, just select the applicable domain, tap in the relevant value and click on the action button. Editing is just as simple, and you can easily set any number of AAAA records or change any AAAA records, all on one easy to access page.

CNAME Record

CNAME is responsible for the aliases of a real host name given to a computer, CNAME stands for Canonical Name Records. CNAMEs are important when a DNS server points multiple domain names to the same IP address. Note that a single computer can have an unlimited number of CNAME aliases but for every CNAME alias there must be a separate CNAME record in the database.

Plesk offers an advanced Custom DNS Manager tool which lets you add, change or remove CNAME entries with just a few clicks of the mouse. Adding a CNAME record is easy, just log into the web hosting control panel and find the Custom DNS Records area, here just choose CNAME from the drop-down list of “Types”.

Once there you must add a URL where your domain will be pointed to and also specify TTL, though TTL is set to 3600 by default.

There are a lot of reasons why you may need to set a CNAME for your domain. For example, you might want to refer visitors to a subdomain to a different server, so your CNAME can point the subdomain to that server. CNAMEs are also useful when you want to create a generic name or when you’ve renamed a host but you don’t need its current name any longer.

The Custom DNS Records page on the Plesk hosting control panel allows you to set up your choice of CNAME for all of your domains. You just need to choose the domain name and add the required CNAME record entry.

Note that CNAMEs must always point to either a hostname or to an IP address. CNAMEs cannot point to other CNAMEs because this will cause the DNS lookup to get stuck in a loop. Likewise, no other DNS records should ever point to a CNAME record.

What is a DNAME record?

Very similar to a CNAME record, DNAME records can create an alias for every record for a domain or subdomain. In contrast, CNAMEs only creates an alias for a single name. Note that DNAME records cause a lot of work for domain name resolvers so it is strongly recommended that DNAMEs are only used for a short period of time.

DKIM

DKIM ( DomainKeys Identified Mail ) is a way of checking that the emails you receive haven’t been interfered with en route to you, and that they genuinely do come from the email addresses that they claim to be from. It uses a digitally signed private key that is exchanged between sender and recipient to verify that its bona fide. DKIM helps to protect you from things like spam and phishing attacks—which try to get hold of personal information like your bank account numbers and credit card details.

DNS

Have you ever wondered exactly how your web browser finds the server for a domain name when you enter an address into your web browser? As humans we prefer using memorable domain names like google.com or amazon.com (and there are millions of these). However domain names in text form are not that well suited to computers, network addressing using numerical IP addresses is much more effective.

DNS or the domain name system is the networking tool that matches a domain name to the IP address that corresponds to it. DNS is what helps your web browser find the IP address for the web server that hosts the domain name. In essence, every time you enter a web address into your browser your web server contacts a DNS server to request the IP address for the domain name. By the way, it’s worth noting that every device connected to the internet has an IP address.

Understanding what a DNS server does

It’s easy to compare the way DNS works to a using phone directory: every domain has a matching IP address, just like every name has a matching phone number. In the case of DNS, the IP addresses matching every domain is kept safe and easy to access for anyone. DNS servers, also known as name servers, is what stores these “phone numbers” for IP addresses.

DNS servers are key to a working internet because every time you send a request for a website using a domain name the DNS server first translates the domain name to an IP address and then sends that IP address to your computer, so that your computer can connect to the IP address. Your computer does not directly connect to a domain name.

Whether you visit a website, transfer a file or send an email, it is the DNS server which looks up the IP address for a domain name. Of course, you can avoid generating a DNS query by directly typing the IP address for the website server in your web browser’s address bar. However, it’s not as simple as it sounds because the IP address behind a domain name can change. For big websites you can also find that the website’s domain makes use of multiple IP addresses.

How do DNS servers do their work?

DNS servers co-ordinate two types of internet namespace and name servers save the data for every domain name, including the full DNS records for that domain. It is a very large database and it works smoothly only because there a literally millions of DNS servers which are all interconnected. DNS resolution requests are distributed amongst these millions of DNS servers.

Whenever you access a website or send an email you initiate a DNS lookup request, this involves contacting your local DNS server to see if it knows the IP address of the domain name in question. Your DNS server might have this address, particularly if it is a popular domain name. If it doesn’t it will ask the other DNS server for the information, and yet another, until it finds a DNS server with the information. Your DNS server then returns the IP address to you and also saves it in its local cache in case you want to visit that website again in the future.

DNS Forwarding

Obviously using a good ISP is the best way to start off when you set up a new network, but there is a lot more you can do to speed up your network. A DNS forwarding server is one way in which you can speed up your network – in fact it works so well that it is basically common practice today.

Explaining DNS forwarding

When you want to speed up the DNS name resolution process you should immediately think about DNS forwarding as a solution. DNS forwarding really helps when a user requests a domain name but the user’s DNS server cannot find the matching IP address in its DNS cache, or within its zones of authority. After all, the DNS server is responsible for converting the domain name into the IP address that corresponds to it. Instead, queries for a non-resolvable address can be referred to other name servers using the forward-DNS-resolution-request function.

DNS forwarding is particularly useful where companies and individuals have very large namespaces. Companies that are collaborating can also use DNS forwarding to resolve each other’s namespace, thereby accelerating name resolution if any of the companies are experiencing problems resolving domains.

But how does DNS forwarding actually work?

When internal DNS information is private there can be a big security issue if this information is transmitted online. This can happen when the root hints of the domain query server is exposed to the public because no DNS forwarder is used in the internal network. Secondly, if the prices of the network’s ISP is high or if the connection is slow the lack of an internal DNS forwarder can complicate matters as it leads to more external traffic.

By setting up a DNS forwarder you make it responsible for external traffic. In doing so the DNS forwarder will build an internal cache of external DNS data. In turn it will continue to use this cache of external DNS data to minimize external DNS traffic.

DNS Server

You can think of the domain name system ( DNS ) as a platform that powers the internet as we use it every day. That’s because DNS is responsible for converting the domain name you type into the address bar, or the domain behind the “@” in an e-mail address, into the IP address which enables your computer to locate on of the millions of servers that host internet services. But, like any internet service, DNS is merely a concept – unless there is a server behind the service. This is what a DNS server does.

What DNS servers do

Operating in a hierarchy, DNS servers use private network protocols to facilitate communication amongst DNS servers. First, there are master DNS servers each of which contains the full DNS database of all internet domain names – alongside the corresponding IP address. Also known as root servers, these master DNS servers are owned by agencies that operating independently – and which are based in the US, UK, Japan and Sweden.

Lower-level DNS servers, much higher in number, only keep parts of the DNS database and are owned by private companies, either a business or an internet service provider (ISP). DNS servers can basically be any computer which is registered on the DNS system – as long as the server runs the required special software for DNS servers, software that facilitates DNS resolution from domain name to host IP address. Every DNS server has a public IP and also includes a database of the addresses and network names of other hosts on the internet.

How does a DNS server operate?

Typing the address of a website (which will contain a domain name) into the browser address bar starts the communication between the end-user’s PC and the DNS server. The web browser is the DNS client which sends a request for the DNS data to the DNS server that is operated by the end user’s ISP. This server then searches for a matching IP address in its internal DNS database.

Sometimes no match is found. If that’s the case the request is sent to another low-level DNS server, and if necessary, to a root server. Eventually a matching domain name and accompanying IP address will be found, this data is then sent back to the web browser through the DNS network. This DNS lookup process is called forward DNS, which is different from reverse DNS. In reverse DNS the DNS server also takes a major part in the process.

Setting up a DNS server

It’s not difficult to set up a DNS server. All you need is standard server computing equipment, alongside a special set of software which is designed to handle DNS queries. There are a number of solutions, both commercial and open-source, which offers DNS services.

Microsoft DNS

Microsoft’s DNS server used the Microsoft Windows Server operating system and is the 4th ranking product which offers DNS – the first three is the three versions of BIND: BIND4, BIND8 and of course BIND9. Microsoft based their DNS server on BIND4 when it shipped as a test release with Windows NT 4.0, but Microsoft DNS has evolved significantly in the meantime.

Djbdns

While Microsoft’s products are commercial, djbdns is an open-source solution for DNS servers. Interestingly, it was created by just one person – D.J. Bernstein. The view was that it is one of the most secure DNS server options: there is a price of $1,000 if someone finds a security hole in how it works.

Another feature of djbdns is the modular structure it uses. This reduces the amount of code in the main body of the service and as a result reduces the complexity of the associated daemon.

Dnsmasq

Useful for smaller networks, Dnsmasq provides an IP forwarder as well as a DHCP server. It supports both IPv4 and IPv6 while also facilitating conversion from IPv4 to IPv6, and the other way around. Most popular Linux distros include Dnsmasq and there are also ports that can be used for the common BSD releases, including FreeBSD. Linksys ships Dnsmasq with all of its wireless router products.

EPP key

A code that contains a series of numbers, Extensible Provisioning Protocol keys or EPP keys are required to enable the transfer of domain from one registrar to another. Sometimes people also call the EPP key an authorization code. Transfer Secret Key is another common name for the EPP key.

Your current registrar will generate an EPP key, this code is checked through a global registry to make sure that it is valid. The EPP key is required by your new registrar when you try to transfer a domain to your new registrar. There is a unique EPP key for each domain, and you will never find two EPP keys that are similar. When you transfer a number of domains you will need to get a unique EPP key for each of the domains.

EPP keys are essentially a security measure that prevents the unauthorized transfer of domain names. If you find that someone other than your registrar requests your EPP key you must make sure that the request is not for a fraudulent purpose.

The most obvious reason for making use of an EPP key is the move of a domain name from one registrar to another registrar. Note that you will need to access the administrative email for your domain before you start to make a domain transfer.

Your current registrar is the party that must supply an EPP key to you. You need to log in to your registrar’s website and request an EPP key for transfer. Every registrar must provide some way to obtain an EPP key for transfers.

Note that you need to change your domain’s status to unlocked before you will be able to get an EPP key. Your domain provider’s control panel will enable you to check the status of your domain, and allow you to change it to unlocked if necessary.

When you get your EPP key you can provide it to your new web host, you will get an email to your domain’s administrative email confirming the request.

IANA

It’s worth remembering that while the internet is not centralised, some aspects of the internet including internet infrastructure must be organised centrally in order for the internet to work smoothly. IANA, the Internet Assigned Numbers Authority was founded by the US government as an organization in 1988. It is now managed by ICANN, the Internet Corporation for Assigned Names and Numbers.

IANA is an essential department of ICANN, it is the authority that allocates IP addresses and domains. IANA also performs technical maintenance of some of the most important rules and structures of the internet. These must be co-ordinated internationally and IANA is the international organisation that co-ordinates it.

The DNS root zone is what helps coordinate communication amongst the millions of internet devices. IANA operates the root DNS zone, which includes all the TLDs – IANA maintains and assigns these domains. It also includes management of the .arpa domain, which is for internal infrastructure, as well as the .int domain which is a TLD used for specific international organisations.

In addition to managing TLDs IANA also manages IP address allocation as well as AS numbers. IANA allocates these to the five RIRs, the Regional Internet Registries. RIRs, in turn, can hand over IP addresses to the Internet Service Providers (ISPs) in their local regions.

Furthermore IANA is also responsible for protocol registries, a database of all the codes which are used by the internet protocols we commonly use.

IP

The Internet Protocol ( IP ) is a protocol for addressing and routing the data packets in order let them move across networks and get to proper destinations. IP data is attached in each data packet – so, this sort of data helps routers to transmit packets to the proper place. In fact, every device and domain which connects to Internet has IP address assigned. Data packets are directed to the certain IP attached to those packets, the data goes where is supposed to go. Upon arrival to destination packets are treated differently depending on the transport protocol used with the IP. The most typical transport protocols are TCP/UDP.

On the public internet all IP addresses are both managed and assigned by the IANA, the Internet Assigned Numbers Authority. The IANA delegates its responsibilities to five separate Regional Internet Registries (RIRs). RIRs are globally co-ordinated, collectively responsible for managing IP addresses across the globe. The RIRs allocate IP addresses to ISPs and other entities which are located in their respective regions.

In the present moment there are IPv4 and IPv6 versions of IP protocol, which was initially presented in 1983.