Questions tagged [domain-name-system]
The Domain Name System, usually referred to by the acronym DNS, is a hierarchical, distributed database where the keys are domain names. Questions involving publicly accessible domains should include the real, Fully Qualified Domain Name (FQDN)
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What are SPF records, and how do I configure them?
This is a canonical question about setting up SPF records.
I have an office with many computers that share a single external ip (I'm unsure if the address is static or dynamic). Each computer ...
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Why can't a CNAME record be used at the apex (aka root) of a domain?
This is a Canonical Question about CNAMEs at the apices (or roots) of zones
It's relatively common knowledge that CNAME records at the apex of a domain are a taboo practice.
Example:
example.com. IN ...
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How to use DNS/Hostnames or Other ways to resolve to a specific IP:Port
This is a Canonical Question about DNS/Hostnames resolution to IPs/Ports
Example 1
I'm running a web server on port 80 and another on port 87. I would like to use DNS so that www.example.com goes to ...
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What is a glue record?
This is a Canonical Question about DNS glue records.
What exactly (but briefly) is a DNS glue record? Why are they needed and how do they work?
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Setting the hostname: FQDN or short name?
I've noticed that the "preferred" method of setting the system hostname is fundamentally different between Red Hat/CentOS and Debian/Ubuntu systems.
CentOS documentation and the RHEL ...
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Should we host our own nameservers?
This is a Canonical Question about whether to outsource DNS resolution for ones own domains
I currently have my ISP providing DNS for my domain, but they impose limitations on adding records. ...
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Why is geo-redundant DNS necessary for small sites?
This is a Canonical Question about DNS geo-redundancy.
It's extremely common knowledge that geo-redundant DNS servers located at separate physical locations are highly desirable when providing ...
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How to configure a Windows machine to allow file sharing with a DNS alias
What process is necessary to configure a Windows environment to allow me to use DNS CNAME to reference servers?
I want to do this so that I can name my servers something like SRV001, but still have \\...
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How does ServerName and ServerAlias work?
It's the following part of a virtual host config that I need further clarification on:
<VirtualHost *:80>
# Admin email, Server Name (domain name), and any aliases
ServerAdmin example@...
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Why does DNS work the way it does?
This is a Canonical Question about DNS (Domain Name Service).
If my understanding of the DNS system is correct, the .com registry holds a table that maps domains (www.example.com) to DNS servers.
...
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What is the role of NS records at the apex of a DNS domain?
$ORIGIN example.com. ; not necessary, using this to self-document
$TTL 3600
@ IN SOA ns1.example.com. admin.example.com. (
1970010100 7200 1800 1209600 300)
@ ...
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Top level domain/domain suffix for private network?
At our office, we have a local area network with a purely internal DNS setup, on which clients all named as whatever.lan. I also have a VMware environment, and on the virtual-machine-only network, I ...
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Why is DNS failover not recommended?
From reading, it seems like DNS failover is not recommended just because DNS wasn't designed for it. But if you have two webservers on different subnets hosting redundant content, what other methods ...
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How long does it take for DNS records to propagate?
This is a Canonical Question about DNS Propagation
How long does it take for an the various types of records to propagate?
Do some propagate faster than others?
Why does it take time for DNS records ...
user38535
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Overriding some DNS entries in BIND for internal networks
I have an internal network with a DNS server running BIND, connected to the internet through a single gateway. My domain "example.com" is managed by an external DNS provider. Some of the entries in ...
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Why multiple PTR records in DNS is not recommended?
I often read that using multiple PTR records in a DNS configuration is not recommended.
However, the reasons are often vague, or not so obvious, naming:
"it can cause problems",
"can ...
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Website and Active Directory domain share the same name
In our network the name of the network domain is also the domain of the organization's website (say, example.com). Externally, people can enter example.com to visit our website, but internally, this ...
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What should the order of DNS servers be for an AD Domain Controller and Why?
This is a Canonical Question about Active Directory DNS Settings.
Related:
What is Active Directory Domain Services and how does it work?
Assuming an environment with multiple domain controllers (...
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In DNS can an IN NS point to a CNAME?
Is it allowed to have an NS record be a CNAME? E.g.:
subdomain.example.com. IN NS ns1.example.com.
ns1.example.com. CNAME foo.example.com.
foo.example.com. IN A 10.1....
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DNS just started resolving my server.prod addresses to 127.0.53.53
I have servers named like server.prod.example.com, and I regularly log into them as server.prod. Recently, these hostnames started resolving to 127.0.53.53.
It turns out that ICANN recently enabled ...
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Do the SSH or FTP protocols tell the server to which domain I am trying to connect?
When using the ssh or ftp commands from the Bash shell, does the server that I am connecting to learn of the domain name used? I understand that the domain name is locally translated into an IP ...
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Set root domain record to be a CNAME
I need to create an NS record for a domain that is a CNAME, for the purpose of having two domains pointed at one IP, and not having to maintain the current IP address in two different places.
The DNS ...
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Private IP address in public DNS
We have an SMTP only mail server behind a firewall which will have a public A record of mail.. The only way to access this mail server is from another server behind the same firewall. We do not run ...
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Set up BIND9 as DNS Firewall
With OpenDNS now needing one to be on the pro package to have filtering turned on, being on a tight budget, we are in need of free DNS filtering.
After reading this link on how to block domains with ...
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Is Round-Robin DNS "good enough" for load balancing static content?
We have a set of shared, static content that we serve up between our websites at http://sstatic.net. Unfortunately, this content is not currently load balanced at all -- it's served from a single ...
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CNAME for top of domain?
Is it possible to set a CNAME record at the top of a domain? (i.e. @ CNAME www, @ CNAME foobar.com., etc.)
My ISP says that it's only possible to use CNAME's for subdomains but I've read somewhere ...
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Is a wildcard CNAME DNS record valid?
I know it's valid to have a DNS A record that's a wildcard (e.g. *.mysite.com). Is it possible/valid/advised to have a wildcard CNAME record?
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Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?
Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique.
The usual warning against DNS RR is that it is not ...
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Are IP addresses "trivial to forge"?
I was reading through some of the notes on Google's new public DNS service:
Performance Benefits
Security Benefits
I noticed under the security section this paragraph:
Until a standard system-wide ...
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Why does Heroku warn against "naked" domain names?
I ran across this page in the Heroku docs...
Naked domains, also called bare or apex domains, are configured in DNS via A-records and have serious availability implications when used in highly ...
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How do I set up a "secure" open resolver?
This is a Canonical Question about securing public DNS resolvers
Open DNS servers seem pretty neat and convenient, as they provide IP addresses that we can use consistently across our company ...
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Clarification of why DNS zone files require NS records
This question was originally asked here:
Why do DNS zone files require NS records?
To summarise:
"When I go to my registrar and purchase example.com , I will tell my registrar that my nameservers are ...
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My public website name and AD domain name are the same. How can I get to my external website from inside my network?
I am using my domain example.orgin my firm. I can use www.example.orgto view my website. If I try http://example.org from outsite my firm there is no problem, but if I try it from inside, my windows ...
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Reverse DNS - how to correctly configure for SMTP delivery
I started a new service and we need to send emails to our customers (new account confirms, etc).
My server is known as prod01.bidrodeo.com and resolves to 97.107.134.38 .
For reverse DNS, 97.107....
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Apache: Scammers point dozens of domain names at my dedicated IP. How to prevent this?
For the sake of discussion, pretend that I have an Apache webserver which serves a website at www.example.org. This domain name resolves to the public IP address at 192.168.1.100 (pretend this is a ...
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What is the correct behaviour when Nameservers Change
I have been having some issues with a certain network supplier over unchanged nameservers making my site invisible to their customers. I wouldnt be bothered except that they are one of the largest ...
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Is a CNAME to CNAME chain allowed?
Is it allowed in DNS to have a CNAME record that points to another CNAME record?
The reason we need this is that we have a hostname that we want to be looked up to the IP address of our web server ...
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How long does negative DNS caching typically last?
If a DNS server looks up a record and it's missing, it will often "negatively cache" the fact that this record is missing, and not try to look it up again for a while. I don't see anything ...
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Is dig +trace always accurate?
When the accuracy of a DNS cache is in question, dig +trace tends to be the recommended way of determining the authoritative answer for an internet facing DNS record. This seems to be particularly ...
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How exactly should I set up DNS to delegate authority for subdomains?
I have servers hosted at a hosting provider and they also host the DNS records for my domain names. Now I want to add subdomains that are resolved by my own DNS service. So for example:
the hosting ...
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Why can't a domain's root be a CNAME? [duplicate]
I've just read this question which essentially says that when I set up DNS for example.com, the root record can't be a CNAME, it has to be an A record.
My question is, why?
I'm sure the clever ...
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Naming a new Active Directory forest - why is split-horizon DNS not recommended?
Hopefully, we all know what the recommendations for naming an Active Directory forest are, and they're pretty simple. Namely, it can be summed up in a single sentence.
Use a subdomain of an existing,...
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How does Windows decide which DNS Server to use when resolving names?
What algorithm does Windows use to decide which DNS Server it will query in order to resolve names?
Let's say I have several interfaces, all active, some with no dns server specified, some told to ...
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Do internet standards require reverse DNS for every device?
The requirements surrounding reverse DNS are confusing! People frequently talk about everything breaking if reverse DNS is not present, and that sounds scary. Even in cases where applications don't ...
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Why aren't our DNS records propagating out into the internet?
We run the name servers for our domain on our network. We use bind/named. Lets call the domain example.com. One thing I've noticed recently, when I goto a website like http://network-tools.com and run ...
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How do I enter a strong (long) DKIM key into DNS?
I'm trying to enter a 4028 bit DKIM key into DNS and it seems that I'm exceeding both the UDP 512 byte limit and also the maximum record size for a TXT record.
How does someone properly create a ...
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Geo-DNS providers? [closed]
We've got a website visited by users mainly in the USA and UK. The site will be run on servers in both these locations.
We would like to use a DNS service to direct users to the nearest server, but ...
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Using .local for internal websites [duplicate]
Is it okay to use app.mycoolname.local for URLs that are private / internal?
We have several applications that are web based, but they are private apps and are not exposed to the public.
We have ...
Brian
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How browsers handle multiple IPs [closed]
Can someone direct me to information on exact browsers behavior when browser gets multiple A records for a given hostname (say ip1 and ip2), and one of them is not accessible.
I interested in EXACT ...
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How can I manage all of my domains with minimal configuration?
This is a Canonical Question about DNS server administration.
I have one hundred or so domains. All of these domains need to be configured identically, but it seems like a huge waste of time to have ...
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