DNS FAQs

DefinitionsGeneralTechnical


What are A Name records?

Address, or "A" records, map the name of a machine to its numeric IP address. In clearer terms, this record states the hostname and IP address of a certain machine. To "resolve" a hostname means to find its matching IP address. This is the record that A NAME server would send another name server to answer a resolution query. The record below is an example of how an A record should look:

www.safeDNS.co.uk IN A 81.201.128.1333

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What are C Name records?

Canonical or "CNAME" records simply allow a machine to be known by more than one hostname. There must always be an A record for the machine before aliases can be added. The host name of a machine that is stated in an A record is called the canonical, or official name of the machine. Other records should point to the canonical name. Here is an example of a CNAME:

www.safeDNS.co.uk IN CNAME demo.safeDNS.co.uk


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What are MX Name records?

Mail Exchange or "MX" records are far more important than they sound. They allow all mail for a domain to be routed to one host. This is exceedingly useful -- it abates the load on your internal hosts since they do not have to route incoming mail, and it allows your mail to be sent to any address in your domain even if that particular address does not have a computer associated with it. Here is an example of a MX NAME:

IN MX 10 punt-1.mail.magicmail.co.uk

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What are NS Records?

Name Server or "NS" records are imperative to functioning domain name system entries. They are very simple; they merely state the authoritative name servers for the given domain. There must be at least two NS records in every entry. UKFast NS records look like this:

IN NS ns0.ukfast.net
IN NS ns1.ukfast.net

However, if you take the branded version with UKFast, your NS records would be on the following basis:

IN NS ns0.yourcompany.co.uk
IN NS ns1.yourcompany.co.uk

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What are Txt and SPF Records?

Sender Policy Framework or "SPF" fights return-path address forgery and makes it easier to identify spoofs. SPF records are DNS TXT resource records that provide a list of servers that may legitimately send mail on behalf of a domain. This allows domain owners to identify sending mail servers in DNS. SMTP receivers verify the envelope sender address against this information, and can distinguish authentic messages from forgeries before any message data is transmitted. By correctly setting up your SPF records, you are contributing to the worldwide fight against the current spam epidemic.

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What are SRV Records?

A Service or "SRV" record is intended to provide information on available services. A SRV record has four fields and a unique system for naming. The naming system is an underscore followed by the name of the service, followed by a period, and underscore, and then the protocol, another dot, and then the name of the domain.

The four fields are.
1. Priority, just AS in MX records
2. Weight, used to determine relative capacity between to SRV fields with the priority. Hits will be assigned proportionately by weight, allowing a powerful and a weak server to share appropriate loads.
3. Port, the port of the service offered
4. Hostname

For Example
_http._tcp.example.com. SRV 10 5 80. www.example.com


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What is a Recursive DNS?

It is a server that can process requests for domains for which it isn't authoritative and which contacts other DNS servers to resolve a given node. As standard our Domain name servers have recursion disabled and cannot process requests unless they're for a requested domain that our servers are authoritative for. It is up to the discression of the Technical Director as to whether we will enable Recursive DNS.

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What is DNS?

The DNS (domain name system/server) is the way that Internet domain names are located and translated into IP addresses - essentially it is nothing more than a directory distributed throughout the Internet.

If DNS were to fail, you would not be able to find any Websites which are hosted on a different network and emails would be undeliverable. So it is really important.


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Where is safeDNS hosted?

Reliability is everything with DNS. To maximise and guarantee up-time, safeDNS is located in 2 separate data-centres, in London and Manchester. Each location is equipped with their own UPS (uninterrupted power supplies) Back up Generators, Early warning Fire Detection systems, coupled with unparalleled connectivity on the UKFast backbone. All the servers in the safeDNS solution are RAID5, each with it's own dedicated back up server. It is company policy to have duplicate machines available and spare parts to insure that even in the worst case scenario the solution remains redundant.

The servers, switches and routers in the safeDNS solution are monitored around the clock 365 days a year. Our engineers are at hand to make sure that safeDNS remains the most robust managed DNS system in the UK.

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How long does it take for my DNS changes to take effect?

All changes to DNS carried out with safeDNS occur in real time but due to propagation it may take several hours on the Internet. To find out more about propagation click the link.

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Where are the Name Servers physically located?

NS0.ukfast.net is in Manchester
NS1.ukfast.net is in London

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What needs to be done to set up my Branded NameServers?

To start the process, the domain you wish to use for your Branded Nameservers must be moved under the control of UKFast.

For a UK domain, please change the TAG to UKFAST
For a US Domain, please transfer the domain into our eNom account.

We will then setup the unique IPs on the DNS Server as well as setting up Reverse DNS.
Finally, we will create the glue records.

Alternatively, if you are unable or unwilling to get your existing IPS to transfer your domain to UKFast, you can request they set up the glue records once we have provided the IP address.

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What type of DNS records can I manage?

The SafeDNS DNS server manager supports A, MX, NS, CNAME and TXT records.


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How does DNS work?

DNS is the basic method which allows a domain name to lead customers to your website as a they attempt to log onto your site.

Every time you enter a domain name you use the Internet's DNS Servers to translate the domain name into the IP address to find the web page.

To determine which primary name server contains your domain name records, a local name server contacts the root domain name server.

The root domain name server then returns the IP address of the primary name server responsible for the domain being requested.

The primary name server becomes the next machine contacted by the local name server.

The primary name server holds the IP address for the domain name and satisfies the the local name server's request.

Then the local name server can finally return to the web browser with the IP address.

Using the IP address, the web browser can then contact your company web server and retrieve your web pages.


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