The Basics of DNS
IPv4
IPv6
IPv6 was first developed in the 1990s. The assumption that IPv4’s 4.3 billion address capacity would be reached due to the ever-increasing number of devices requiring addresses prompted the development of IPv6. IPv6, or Internet Protocol Version 6, is a protocol that was developed IPv4 is replaced, and the address exhaustion problem is overcome by employing a 128-bit address space instead of the 32-bit address space used by IPv4. IPv4 may provide exponentially more addresses than IPv4 (3.4 undecillion addresses) due to its wider address space (Kralicek, 2016). Each of the eight sets of IPv6 addresses contains four hexadecimal digits. Four bits can be represented by each hexadecimal digit. x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x:x: Each x represents a 16-bit part that can be represented by up to four hexadecimal digits, with colons between the sections (Cisco Press, 2017).
Some Advantages of IPv6 over IPv4
Apart from the increased address space, IPv6 has a few other advantages over IPv4. When IPv4 was designed in the 1970s, there was less emphasis on security than there is today. IPv4 required the addition of security, whereas IPv6 was created with security built-in. IPv6 employs IPSec to enable end-to-end packet encryption, ensuring that data is safely transported across the network. Another benefit of IPv6 is that it does not require Network Address Translation (NAT). NAT for IPv4 is a technique for dealing with the limited amount of IP addresses available. NAT is used in routers that connect two networks. It converts local network private addresses into globally unique addresses that can be routed to other networks. The router that connects the network to the outside world advertises only one address when using NAT. When incoming packets are received, NAT translates them once more to guarantee that they are delivered to the relevant network device. IPv6 eliminates the requirement for NAT since it solves the problem of limited address space. Removing NAT from a network is advantageous since it eliminates a single point of failure. Furthermore, without NAT, less processing is required, leading in increased efficiency and possibly faster data transmission speeds. IPv6 provides more configuration options than IPv4. In IPv4, network administrators can allocate IP addresses manually or through the Dynamic Host Configuration Protocol (DHCP) (DHCP). DHCP allows a pool of temporary IP addresses to be assigned automatically. After the “IP Lease” expires, the IP addresses are returned to the pool for reassignment. Stateless IP Address Autoconfiguration (SLAAC) is a feature of IPv6 that allows IP addresses to be assigned automatically (Hagen, 2014). When a new device is added to a network, SLAAC allows it to receive its own IP address without requiring DHCP. Broadcast transmissions are supported by IPv4, while multicast transmissions are supported by IPv6. Broadcasting is the transmission of data packets to all users on a network without the need to address the packets individually or wait for a response from the users. A broadcast address is used in IPv4 to send a broadcast. IPv6, on the other hand, was created with multicast in mind. Multicast transmits data to a preset set of hosts by adding their addresses to multicast groups (Juniper, 2021). Because multicast allows senders to choose who gets the transmission, it is more efficient than broadcast. This improves network efficiency by removing the requirement for network nodes to continuously listen for and receive broadcast traffic that may or may not be required. Another distinction between IPv4 and IPv6 is the Quality of Service (QoS). QoS is a traffic management technique that ensures a certain level of performance for specified applications. For bandwidth-intensive applications like Voice Over Internet Protocol, QoS is used (VOIP). VOIP (Voice over Internet System) is a protocol that allows phones to communicate over the internet, eliminating the need for traditional Plain Old Telephone Service (POTS) phones. The voice quality of VOIP can be degraded if data transfer performance is poor (i.e. delay or jitter). QoS data is included in IPv4 packets, and routers are set up to prioritise vital traffic (like VOIP traffic). QoS is integrated into IPv6.
Diferences between IPv4 DNS and IPv6 DNS
When it comes to DNS, the transition from IPv4 to IPv6 has no effect on the user experience. The user will continue type in the same hostnames as before, and the IP address will be resolved in the background, just like with IPv4. The procedure of configuring IPv6 DNS is quite similar to that of configuring IPv4 DNS. In DNS, there are two types of lookup zones: forward and reverse zones. Forward lookup zones convert hostnames to IP addresses, whereas reverse lookup zones convert IP addresses to hostnames. ‘A Records’ are used to represent forward lookup zones in IPv4. Only 32-bit IP addresses can be stored in ‘A Records.’ DNS needed a system that could accept the larger IPv6 addresses, which are 128 bits long. The ‘AAAA’ (Quad A) record was introduced as the answer (Liu, 2011). BIND (Berkeley Internet Name Domain) is an open-source DNS server that is widely used. IPv6 and ‘AAAA’ Records are presently supported by BIND. Hostnames are translated to IP addresses via reverse zone lookups. Reverse zone lookups in IPv6 are done via the IP6.ARPA domain (Pete, 2004). The word ARPA stands for Address and Routing Parameters Area. In the same way, IPv4 uses the IP4.ARPA domain for reverse lookups.
Advantages of IPv6 DNS
The fundamental benefit of IPv6 DNS is that it enables IPv6’s advantages over IPv4. These include a large address space, the elimination of NAT, setup benefits, multicast support, and QoS, among others. Another advantage of IPv6 DNS is that it is more secure than IPv4 DNS.
Disadvantages of IPv6 DNS
The fact that IPv6 DNS is not backward compatible with IPv4 is a negative. DNS servers must reply to both IPv6 and IPv4 requests since the IPv6 rollout is a long process that will take several years. This need results in less efficiency until the conclusion of the IPv6 migration. Subnetting may become less common as a result of IPv6. In IPv4, subnetting is frequently used to segment networks in order to maximise the efficiency of the available IP space. System administrators may limit this behaviour because IPv6 has an exponentially bigger number of available IP addresses. Subnetting has the unintended consequence of minimising unwanted online traffic. Less subnetting would result in a higher traffic burden on DNS servers, which would be a drawback. Because IPv6 does not require or permit NAT, a security feature found in NAT is not applicable to IPv6. The internal network IP addresses and port numbers are hidden behind NAT so that they are not visible to the outside world. The fact that IPv6 does not support this could be viewed as a drawback. This disadvantage is debatable because the concealment of internal network IP addresses is not considered a reliable security feature. As previously stated, IPv6 assigns IP addresses automatically using SLAAC. The IPv6 end nodes choose their own IP addresses via SLAAC. The DNS servers still require reverse DNS records for the IP specified using SLAAC, but these records are not available (Internet Society, 2014). This disadvantage is no longer relevant because several strategies for addressing it have been recommended and implemented.
How IPv6 May change the way networks use DNS
The benefits of IPv6 such as less NAT and more IP space, combined with the proliferation of new connected IoT devices, will result in dramatically increased traffic to DNS servers. This rise will almost certainly necessitate scaling up the DNS server infrastructure to match the demand. There will be a need for more processing power and storage. The DNS hierarchy is a tree with controlled zones at the top and root servers at the bottom. There are only 13 root server addresses due to IPv4 constraints, however there are over 600 individual root servers dispersed over the world. The rise in internet traffic and the removal of IPv4’s constraints may need the addition of more root server addresses.
