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Question Difference between the IP addresses and DNS servers?

rdn24

Junior Member
Mar 12, 2016
24
0
66
I have a question about IP addresses and DNS servers in the screenshot below. This is screenshot from robtex.com using corel.com as an example.
  1. What's the difference between the IP numbers below and Name servers? is it saying there are 4 IP's to corel.com and there are 4 DNS servers (which are separate from corel.com)?
  2. Would I be correct in saying corel.com and the DNS server below are two different nodes?
  3. How does a company get assigned more than 1 DNS server? Do they call their ISP and request more?

    Capture.JPG
 

mxnerd

Diamond Member
Jul 6, 2007
6,138
883
126
DNS server is like 411 or 555-1212 directory service at different locations. It keeps domain name/host name and IP address pair registry entries.

The IP addresses already changed. The IP database for corel.com at robtex.com probably is stale. Different IP addresses usually just mean different machines.

You were correct that 4 IP addresses here mean 4 DNS servers.

At the beginning, when you register a domain, it's required to have at least 2 DNS servers. But nowadays it seems all ISP provides 4.

Code:
P:\APPS\CMD Promopt_CD\Cmder
λ nslookup
Default Server:  UnKnown
Address:  192.168.0.21

> server 8.8.8.8
Default Server:  dns.google
Address:  8.8.8.8

> ns-90.awsdns-11.com
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    ns-90.awsdns-11.com
Addresses:  2600:9000:5300:5a00::1
          205.251.192.90

> NS-847.AWSDNS-41.NET
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    NS-847.AWSDNS-41.NET
Addresses:  2600:9000:5303:4f00::1
          205.251.195.79

> NS-1216.AWSDNS-24.ORG
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    NS-1216.AWSDNS-24.ORG
Addresses:  2600:9000:5304:c000::1
          205.251.196.192

>  NS-1983.AWSDNS-55.CO.UK
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    NS-1983.AWSDNS-55.CO.UK
Addresses:  2600:9000:5307:bf00::1
          205.251.199.191
 
Last edited:
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rdn24

Junior Member
Mar 12, 2016
24
0
66
DNS server is like 411 or 555-1212 directory service at different locations. It keeps domain name/host name and IP address pair registry entries.

The IP addresses already changed. The IP database for corel.com at robtex.com probably is stale. Different IP addresses usually just mean different machines.

You were correct that 4 IP addresses here mean 4 DNS servers.

At the beginning, when you register a domain, it's required to have at least 2 DNS servers. But nowadays it seems all ISP provides 4.

Code:
P:\APPS\CMD Promopt_CD\Cmder
λ nslookup
Default Server:  UnKnown
Address:  192.168.0.21

> server 8.8.8.8
Default Server:  dns.google
Address:  8.8.8.8

> ns-90.awsdns-11.com
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    ns-90.awsdns-11.com
Addresses:  2600:9000:5300:5a00::1
          205.251.192.90

> NS-847.AWSDNS-41.NET
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    NS-847.AWSDNS-41.NET
Addresses:  2600:9000:5303:4f00::1
          205.251.195.79

> NS-1216.AWSDNS-24.ORG
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    NS-1216.AWSDNS-24.ORG
Addresses:  2600:9000:5304:c000::1
          205.251.196.192

>  NS-1983.AWSDNS-55.CO.UK
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    NS-1983.AWSDNS-55.CO.UK
Addresses:  2600:9000:5307:bf00::1
          205.251.199.191
to confirm the corel IP addresses and DNS servers are different nodes? I assume yes.

if the ISP assigns you DNS servers, is it safe to say if the ISP goes down so does your DNS servers which mean you site is no longer available?

thank you
 
Last edited:

mxnerd

Diamond Member
Jul 6, 2007
6,138
883
126
Sorry, those 52.xx.xx.xx IP are host IP, not DNS server's IP addresses.

Code:
C:\Windows\system32>nslookup

Default Server:  UnKnown
Address:  192.168.0.21

> server 205.251.192.90
Default Server:  ns-90.awsdns-11.com
Address:  205.251.192.90

> corel.com
Server:  ns-90.awsdns-11.com
Address:  205.251.192.90

Name:    corel.com
Addresses:  52.70.23.216
          52.44.24.20
Propagation check:
 
Last edited:

mxnerd

Diamond Member
Jul 6, 2007
6,138
883
126
to confirm the corel IP addresses and DNS servers are different nodes? I assume yes.
Yep
enter corel.com at the following website
https://www.dnsqueries.com/en/dns_lookup.php, choose ALL for type for additional info.

corel.com name server IP addresses have been found by using nslookup tool and shown earlier
NS-90.AWSDNS-11.com 205.251.192.90
NS-847.AWSDNS-41.NET 205.251.195.79
NS-1216.AWSDNS-24.ORG 205.251.196.192
NS-1983.AWSDNS-55.CO.UK 205.251.199.191

if the ISP assigns you DNS servers, is it safe to say if the ISP goes down so does your DNS servers which mean you site is no longer available?
Not necessarily. Domain registration situation could be different for everyone.

Your ISP could be your domain registrar, domain hosting provider and hosting your domain DNS servers, but they could all from different ISP providers/vendors, they don't have to be the same. You can even host your own DNS server and websites, but DNS servers need public static IP addresses, it's a requirement, and at least 2.
 
Last edited:

mv2devnull

Golden Member
Apr 13, 2010
1,380
81
91
Code:
C:\> nslookup -type=NS corel.com
Server:  ***
Address:  ****

Non-authoritative answer:
corel.com       nameserver = ns-1216.awsdns-24.org
corel.com       nameserver = ns-90.awsdns-11.com
corel.com       nameserver = ns-847.awsdns-41.net
corel.com       nameserver = ns-1983.awsdns-55.co.uk
As above, we are told that these four nameservers are somehow associated with "corel.com"

Lets ask from one of them (ns-1983.awsdns-55.co.uk) the address of "corel.com":
Code:
C:\> nslookup corel.com ns-1983.awsdns-55.co.uk
Server:  UnKnown
Address:  2600:9000:5307:bf00::1

Name:    corel.com
Addresses:  52.44.24.20
          52.70.23.216
Lets ask from Google (8.8.8.8) the same question:
Code:
C:\> nslookup corel.com 8.8.8.8
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    corel.com
Addresses:  52.44.24.20
          52.70.23.216
Notice the difference? Google gives Non-authoritative answer:

Google says that "others told" that the addresses are ...
ns-1983.awsdns-55.co.uk says that "it knows for certain" that addresses are ...

Those four DNS servers are the ones that all other DNS servers turn to, when they can't remember what "corel.com" is. The authority on that matter.
 
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mv2devnull

Golden Member
Apr 13, 2010
1,380
81
91
More fun:
Code:
$ host ns-1216.awsdns-24.org
ns-1216.awsdns-24.org has address 205.251.196.192
ns-1216.awsdns-24.org has IPv6 address 2600:9000:5304:c000::1
$ host ns-90.awsdns-11.com
ns-90.awsdns-11.com has address 205.251.192.90
ns-90.awsdns-11.com has IPv6 address 2600:9000:5300:5a00::1
$ host ns-847.awsdns-41.net
ns-847.awsdns-41.net has address 205.251.195.79
ns-847.awsdns-41.net has IPv6 address 2600:9000:5303:4f00::1
$ host ns-1983.awsdns-55.co.uk
ns-1983.awsdns-55.co.uk has address 205.251.199.191
ns-1983.awsdns-55.co.uk has IPv6 address 2600:9000:5307:bf00::1
All four DNS addresses belong to same subnet, CIDR 205.251.192.0/18, that is registered to Amazon.com Inc. No surprises there.

Code:
$ host 52.44.24.20
20.24.44.52.in-addr.arpa domain name pointer ec2-52-44-24-20.compute-1.amazonaws.com.
$ host 52.70.23.216
216.23.70.52.in-addr.arpa domain name pointer ec2-52-70-23-216.compute-1.amazonaws.com.
"Real" names of those two IP addresses are both *.amazonaws.com. Again, no surprise; Amazon hosts Corel's servers.

The two addresses are probably not in the same subnet (guess: 52.0.0.0/10 and 52.64.0.0/12), nor in same datacenter.

One IP address can have multiple names. One name can have multiple IP addresses (for HA/load balancing).
 
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rdn24

Junior Member
Mar 12, 2016
24
0
66
Code:
C:\> nslookup -type=NS corel.com
Server:  ***
Address:  ****

Non-authoritative answer:
corel.com       nameserver = ns-1216.awsdns-24.org
corel.com       nameserver = ns-90.awsdns-11.com
corel.com       nameserver = ns-847.awsdns-41.net
corel.com       nameserver = ns-1983.awsdns-55.co.uk
As above, we are told that these four nameservers are somehow associated with "corel.com"

Lets ask from one of them (ns-1983.awsdns-55.co.uk) the address of "corel.com":
Code:
C:\> nslookup corel.com ns-1983.awsdns-55.co.uk
Server:  UnKnown
Address:  2600:9000:5307:bf00::1

Name:    corel.com
Addresses:  52.44.24.20
          52.70.23.216
Lets ask from Google (8.8.8.8) the same question:
Code:
C:\> nslookup corel.com 8.8.8.8
Server:  dns.google
Address:  8.8.8.8

Non-authoritative answer:
Name:    corel.com
Addresses:  52.44.24.20
          52.70.23.216
Notice the difference? Google gives Non-authoritative answer:

Google says that "others told" that the addresses are ...
ns-1983.awsdns-55.co.uk says that "it knows for certain" that addresses are ...

Those four DNS servers are the ones that all other DNS servers turn to, when they can't remember what "corel.com" is. The authority on that matter.
Im still trying to wrap my brain around multiple DNS servers (back to basic's I guess). For example, since corel is located on AWS. Did amazon say (not literally), "hey, since you're our customer, were giving you 4 DNS servers".

1. would these DNS servers be the "resolvers? (ISP DNS)
2. why 4 DNS servers, is this amazon's way of just trying to add protection in case one of the DNS servers go down?
 
Last edited:

JackMDS

Elite Member
Super Moderator
Oct 25, 1999
29,175
285
126
Unless you have a specific problem with the DNS it really used by your system does not really matter.

DNS server is Not like server storage space given to you (like One Drive, or AWS). It just a service to resolve the Traffic on the Internet and almost all of the brand name DNS are fast and do the same job.


:cool:
 

mxnerd

Diamond Member
Jul 6, 2007
6,138
883
126
Multi DNS servers are for load balancing and redundancy, there is no limit how many DNS servers a provider can provide.


Ex: dynu.com registered 7 DNS servers.


==


The Hitchhiker's Guide to the Windows Naming Resolution (DNS name resolution is just part of it)
DNS server existed way before Windows came out.

==

 
Last edited:

fkoehler

Member
Feb 29, 2008
136
79
101
Cool, I find this stuff quite interesting 😉
Check out DNS Tiering, also Root Server:
ROOT (1).png

The DNS servers you mentioned are most likely AWS Route 53 Resolvers.
AWS most likely has 4 for redundancy purposes, and those are supporting a lot more than just Corel.
All 4 of those appears to hit Amazon-02 in Chicago, at least initially. I would have thought they'd have been located a bit more redundantly.

OK, thats a cool website, have to remember it.

"The IP numbers are 34.227.243.142, 52.21.58.253, 52.44.24.20 and 52.70.23.216. The PTR of the IP numbers is ec2-34-227-243-142.compute-1.amazonaws.com. The IP numbers are in Ashburn, United States."

Screenshot from 2021-05-25 22-46-43.png
 
Last edited:

ch33zw1z

Lifer
Nov 4, 2004
33,915
12,702
146
IMO, great thread, should be stickied :).

good links with lots of info. It's probably been 20 years since my education on DNS. Most underappreciated service online :p
 

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