What is TCP/IP?
Transmission Control Protocol/Internet Protocol (currently in revision 4, known as IPv4, and sometimes called 4bone) - is a communication language that is used for transmitting data over networks. It is the main protocol for the Internet. TCP/IP is a set of instructions that describes how packets of information are sent across multiple networks. The TCP part deals with the verifying delivery of the packets. The IP part refers to the moving of data packets between nodes.
What is TTL?
TTL is a setting placed on all Internet Protocol packets in the form of a numerical value to limit how long the packet ‘lives’ inside the Internet transmission system. This number value is known as the hop limit. Here's how TTL works:
- DNS Records: When you visit a website, your computer sends a request to a DNS resolver (a server that translates domain names into IP addresses). The DNS resolver looks up the appropriate DNS records associated with the domain to find the corresponding IP address.
- Caching: To improve efficiency and reduce network traffic, DNS resolvers and other systems cache DNS records for a certain period. This caching helps speed up subsequent requests for the same domain. However, because IP addresses can change or records can be updated, it's important to have a mechanism to control how long cached records are considered valid.
- TTL Value: The TTL value is set by the domain owner in the DNS records. It indicates the time period (in seconds) that a DNS record can be cached by other systems. For example, if a DNS record has a TTL of 3600 seconds (1 hour), it means that the record can be cached by DNS resolvers and other systems for up to 1 hour before they should check for updated records.
- Expiration and Refresh: Once the TTL period expires, the cached record is considered stale. After expiration, DNS resolvers will query the authoritative DNS servers again to get the most up-to-date record. This process is known as "refreshing."
What is A record?
The ‘A’ in A Record stands for ‘address.’ This is the most popular DNS record type. Its function? Connecting your website domain or subdomain names, such as example.com or blog.example.com, to a numerical IPV4 address such as 127.0.0.1. Think of this as the home address of your website.
Note that an ‘A’ record shows that server’s IP address location when you connect your website to a hosting service. Other names commonly used to describe ‘A’ records include an ‘Address Mapping Record’ and a ‘DNS host record.’
What is AAAA record?
This behaves the same as the ‘A’ record but points the domain to an IPv6 address. The difference between IPv4 and IPv6 is the length of the IP address name from 32 bit to 128 bit consecutively. Because many domains use domain registrars, their name servers have an IPv4 address, so an AAAA record is not present.
- Note: You’d only need to change an A or AAAA record type if you switched to a new hosting provider, changed servers to a personal name server, or the IP of your hosting provider changed.
What is CNAME record?
To understand CNAME records, you first need to know about domain configuration - or the hierarchy of DNS records. Think of the A record as the one sitting at the top of the naming tree.
When you want to add applications, a typical example of their requirements is to link www.example.com to your domain. So the CNAME record makes sure www.example.com knows example.com (the ‘A’ record name)is the true (or ‘naked’) domain. CNAME stands for “canonical name” and will always point one name used by your website to your A record.
- Note: If you change your hosting and therefore change your domain’s IP address, you only need to update the A/AAAA record IP address because a CNAME record will automatically change as well.
What is MX record?
It’s helpful to remember to view the DNS as the map to your services. Your MX or mail exchange DNS record always exists when you buy a domain, but you need to add your client-server mail name (e.g., is it Private Email, Gmail, Protonmail, or something else) to the record, so the domain knows which client to use. You need to have these records configured to receive mail to your domain.
The DNS MX record needs the name of your chosen mail servers and something called a “priority value’ to work. Different mail providers have a different number of servers, and some have only one. So look to your provider to find out how to fill in your MX records and prioritize their mail servers in the correct order.
- Note: For anyone confused about MX records set up, representatives can help you select your mail service and get things working. You might need to delete the CNAME record to get your mail working if the CNAME record and MX records are created for the same host.
What is SRV record?
A service record (SRV) is a specification of data in the Domain Name System defining the location (i.e., the port number) of servers for specified services (e.g., Minecraft). Think of this as ‘plugging in’ a service to a port.
What is TXT record?
Provides the ability to associate other services, or sometimes your mail service, to your domain. This is to help humans using words recognize which server (or software) is using their system. You can add many TXT records to describe other numerical ideas.
Some places you might see a TXT record are with an SPF (Sender Policy Framework), DKIM (DomainKeys Identified E-mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) purposes. Most DNS hosting providers give clear instructions if you need to change these records, or better still, provide automatic transfer tools to help you out.
What is PTR record?
This ‘pointer’ record converts an IP address into a domain name. It’s known as a reverse DNS entry check to verify if a server matches the domain it claims to be from. It’s an extra check used as a security measure.
What is SOA record?
This record stores important information about the DNS zone for your domain, including the person responsible for the entire zone. Each zone must have an SOA record, but it’s unlikely you’ll have to create an SOA record directly—unless the responsible person is you. An interesting thing about SOA records is they are always distributed with a zero TTL to prohibit caching. This record cannot be adjusted or interfered with but is limited to traveling only to one server at a time.
What is AFSDB record?
This record is used for clients of the Andrew File System (AFS) developed by Carnegie Mellon. You’ll see this in your records if you add in music and video streaming plugins.
What is APL record?
The ‘address prefix list’ specifies lists of address ranges and is commonly used if you want a closed system of users, like at the office and across multi-sites or delivery driver devices.
What is DCHID record?
When a non-Windows server contacts a Windows host in a dynamic IP network (like a multi-site office where everyone uses different devices and operating systems), this record stores ‘A’ records and points ‘PTR’ records for the Dynamic Host Configuration Protocol (DHCP). It’s a type of Resource Record to help things run smoothly in a network, ensuring all DNS records refresh and only authorized devices run with the verified domain. This prevents the crime of cybersquatting or ‘name squatting whereby someone slips into the network and borrows your domain name to make a profit, pretending to be from your organization.
What is DNAME record?
The ‘D’ stands for delegation and allows you to create a new tree for subdomains. If you have a domain example.com and you add cats.example.com as an ‘A’ record, but you want to have dogs in there too, you could create a subdomain using a DNAME record. This record works just like a CNAME and will send all lookups for dogs.example.com and CNAME lookups for cats.example.com to the same IP address for all parts of example.com.
What is HIP record?
A ‘Host identity protocol’ record separates the roles of an IP address by the device. This record is used most often in mobile computing.
What is RP record?
The RP-record type makes it possible to identify the responsible person for individual hostnames within a specific DNS zone.
What is SSHFP record?
This record stores the ‘SSH public key fingerprints’; SSH stands for Secure Shell, and it’s a cryptographic networking protocol for secure communication over an unsecured network.
What is DNSSEC records?
When DNSSEC protocols apply to your website’s DNS, you will see these record types:
- DNSKEY record: To prevent cybercrime and stop your users from being redirected to a false website, This record contains a crypto key to verify you have DNSSEC (Domain Name System Security Extension) signatures.
- NSEC record: The ‘next secure record’ is used to return approved DNS resource records listed by DNSSEC and disprove others.
- RRSIG record: This stands for ‘resource record signature’ and authenticates records that use digital signatures under DNSSEC.