PowerDNS (pdns) is an open source authoritative DNS server that works as an alternative to traditional BIND (named) DNS. PowerDNS offers better performance and has minimal memory requirements. PowerDNS also works with many supporting backends ranging from simple zone files to complex database setups as well as various SQL platforms (Mysql, MariaDB, Oracle, PostgreSQL). Continue reading “What is Power DNS?”
When using custom name servers, it is essential to update the DNS in cPanel/WHM, doing so, is a component of hosting your own DNS. Continue reading “Editing DNS Zone Files in WHM/cPanel”
Do you ask yourself, “What is DNS?” “Do I need to use DNS?” Do you feel confused? In some cases, DNS can be convoluted and complicated. Let’s talk about Domain Name System (DNS) services. When you need to access a website, you type the domain name, such as www.google.com, into the web browser instead of typing an IP address. A conversion happens between www.google.com to 18.104.22.168, an IP, which designated to a device on the Internet. This conversion is a DNS query, an integral part of devices connecting with each other to communicate over the internet. To understand the DNS query process, let’s talk about how a DNS query routes through different components.
A DNS Zone is a portion of the DNS namespace that is managed by an organization or administrator. It serves as an administrative space with granular control of DNS components and records, such as authoritative nameservers. There is a common misconception that a DNS zone associates only with a single domain name or a single DNS server. In actuality, a DNS zone can contain multiple domain and subdomains. Multiple zones can also exist on the same server. Information stored for a DNS zone lives within a text file called a DNS zone file. Continue reading “DNS Zones Explained”
DNS is typically used to resolve a domain name to an IP address. This act is known as a forward resolution and enacted every time you visit a site on the internet. Reverse DNS (rDNS), as its name implies, is a method of resolving an IP address to a domain name.
The DNS records used for resolving an IP address to the domain name are known as pointer (PTR) records. A particular type of PTR-record is used to store reverse DNS entries. The name portion of the PTR-record is the IP address with the segments reversed and “.in-addr.arpa” added at the end of the record. The “.in-addr.arpa” portion of the record refers to the “address and routing parameter area” (arpa). rDNS uses “in-addr.arpa” for IPv4 and “ip6.arpa” is used for IPv6 addresses.
For example, the reverse DNS entry for IPv4 IP “22.214.171.124” would be “126.96.36.199.in-addr.arpa”.
The use of reverse DNS is for the same reason as standard (forward) DNS. It is easier to remember and identify a domain name than a string of numbers. rDNS is less critical than forward DNS, as forward DNS records are required to load up a website. Sites will still load fine in the absence of a reverse DNS record.
Email Servers commonly use rDNS to block incoming SPAM messages. Many mail servers are set to automatically reject messages from an IP address that does not have rDNS in place. Though the rDNS record can block spam, it is not a reliable means and is used mostly as an extra layer of protection. It is also important to note that merely enabling rDNS can still result in rejected messages due to a variety of reasons. Additionally, rDNS is also used in logging to help provide human readable data rather than logs consisting entirely of IP addresses.
Reverse DNS lookups query the DNS servers of a domain for a PTR (pointer) record. If the domain’s DNS server does not have a valid PTR record setup, it cannot resolve a reverse lookup. However, if a domain does have a PTR record, you can do a rDNS Lookup by using the method below.
Numerous online tools can be used to perform a rDNS lookup. A few examples of these online tools are linked below:
You can also perform a rDNS lookup manually from command line. In Linux, the command you would use is “dig” with the added “-x” flag.
If you are on a Windows computer, you would typically use the “nslookup” command, though you could also use “ping -a”. An example of the Linux command and its output shown below:
dig -x 188.8.131.52
;<<>> DiG 9.9.4-RedHat-9.9.4-61.el7 <<>> -x 184.108.40.206
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36810
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;220.127.116.11.in-addr.arpa. IN PTR
;; ANSWER SECTION:
18.104.22.168.in-addr.arpa. 21599 IN PTR google-public-dns-a.google.com.
;; Query time: 19 msec
;; SERVER: 22.214.171.124#53(126.96.36.199)
;; WHEN: Wed Jul 18 11:58:54 EDT 2018
;; MSG SIZE rcvd: 93
You can see the full rDNS PTR record for that IP in the “ANSWER SECTION” leading 188.8.131.52 back to the Google subdomain, google-public-dns-a.google.com :
184.108.40.206.in-addr.arpa. 21599 IN PTR google-public-dns-a.google.com.
Liquid Web makes it easy to set up and manage rDNS for your servers IPs. Just follow the steps outlined in our Knowledge Base article below:
Setting up a reverse DNS record is straightforward and can be beneficial to ensure that an IP does indeed belong to the domain it claims. If you are unsure who your DNS provider is, follow our helpful guide in locating where you should add the rDNS record.
Domain Name System Security Extensions or DNSSEC signs DNS Record Sets (RRsets) at each DNS zone level. This allows one to verify the DNS record they are receiving has not been altered.
For example, manage.liquidweb.com has these zone levels:
- Root (.)
- com, org, net
DNS Record Set (RRsets) is a group of records with the same record type, for example all DNS A records are one RRset.
Adding a DNS Zone
What is it?
Glue Records, or Nameserver Glue, relate a nameserver on the internet to an IP address. This relationship is set up at the domain registrar for the main domain on which the nameservers were created.
When you host at Liquid Web you can use our DNS servers to manage all of your domains. Even the ones you bought through other registrars.
The Liquid Web Name Servers (NS) are:
Continue reading “What are the Liquid Web Name Servers (NS)?”
As we learned in our article What Are Domains?, a domain is associated with an IP address that directs visitors to the right location in the Internet that houses your site and its contents. In the same way, a Glue Record binds the IP address to a static cache so visitors can always locate your site without issue. This avoids impossible dependencies for that DNS zone. Your registrar holds the Glue Record and allows traffic to be directed without using the lookup process of DNS. You often see a Glue Record used for nameservers, but it is occasionally in other records depending on circumstances. Continue reading “What is a Glue Record?”