Questions tagged [dns]

This tag should only be used when it's about configuration of DNS on an on topic network device. Any general DNS service related questions are off topic.

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DNS Resolution Process when only part of the Authoritative DNS Servers (Name Servers) for a spefic Domain are reachable from the Internet [closed]

I would like to ask for some clarification on the following situation / Scenario. Let's assume I have a Domain, whose DNS A Records are registered by means of 2 Pairs (4 in total) of Name Servers; ...
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Pros and cons of IP address in service discovery response [closed]

I'm looking at service discovery protocols such as SLP and SSDP for moving closer to zeroconf in lab environment (quite a few IP conflicts lately, wanna do something about it). My biggest problem is ...
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How to trace UDP blocking for DNS port 53 [closed]

Recently both of our DNS servers stopped responding to incoming UDP on port 53, tested with dig and it works with TCP. They both have common ISP. Is there any way to trace route and find out exactly ...
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2answers
41 views

Best way to make a network failsafe?

I have a Debian based machine with 2 completely different network interfaces from 2 different ISPs acting as a backup for my server connection. These have two different IPs (Let's say IP1 and ...
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1answer
19 views

Why can i ping domain from Pfsense diagnostics but not from my desktop?

I'm setting up Pfsense to replace our existing firewall with. Currently the setup is pretty straight forward. I have internet connected to my wan port connected a switch to the lan port connected ...
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25 views

If a server has both IPv4 and IPv6 addresses, how does the DNS determine which to return? See the following example [closed]

These Pings were done at different times of the same day: C:\Users\LPress>ping www.ucla.edu Pinging gateway.lb.it.ucla.edu [164.67.228.152] with 32 bytes of data: C:\Users\LPress>ping www.ucla.edu ...
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1answer
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How can I use 1 static public IP address for multiple private networks in totally different physcical locations?

So, I know that DNS is important in the running of CDN services. DNS allows the routing client traffic to the physically nearest CDN server. Question is, how can I do the same thing without any DNS ...
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1answer
37 views

Able to ping Domain internal address on home network, why? [closed]

I have a strange issue, I am able to ping my company's internal address (ex: hq.mycomapny.com) when I am on my Home network (WI-FI or Enthernet) and NOT connected to the VPN. When I do a ping on the ...
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1answer
89 views

Cisco IOS: DNS Servers via DHCP

Simple question: I have following switch configuration: interface Vlan1 ip address dhcp end ip domain-lookup I receive and IP and DNS servers along with it from our DHCP server. At least Windows ...
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1answer
58 views

What special reserved domain could I use for virtual organization private network? [closed]

Suppose we have a inner-facing network that spans several geographical jurisdiction - this network can only accessed from our offices with special HSM installed, and we want to enable domain-name-...
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2answers
70 views

What are some high-traffic websites that operate with a global anycast IP address?

I've been trying to find an example of an anycast IP address used by a hugely popular service or a website. According to my queries at https://www.whatsmydns.net/ , none of the large sites that are ...
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108 views

LAN to WAN IPv4 address mapped to LAN server through NAT Rules or other

I need to set a rule that allows me to connect BOTH from OUTSIDE the LAN (from the "internet" to the Internal server at IPv4 address 10.64.0.50 via port 22, by running ssh://1.2.3.4 -p 22; AND From ...
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1answer
248 views

DNS expire-entry-timer has negative affect on ASA using FQDN ACL

I have a Cisco ASA using FQDN egress ACLs for a host that changes IP addresses every 10 mins (Apple APNS IP address pool). As soon as the TTL expires for the addresses, my internal server requests a ...
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1answer
67 views

How does a DNS response reach a client behind a NAT?

How does a DNS response reach a client behind a NAT? I'm talking about DNS queries using UDP for transport with a server that is not in the same network as the client. Does the NAT correlate the ...
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1answer
34 views

Why does www DNS record propagate faster than @? [closed]

I've recently had to move a DNS ownership from one DigitalOcean account to another. During this process I've noticed that the www A DNS record propagates a lot faster than the @ A DNS record. Why ...
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1answer
83 views

Dynamic DNS and VPN [closed]

I have a few PCs/services that I want to access remotely, which are inside a VPN and gets assigned local IP addresses using DHCP. How can I setup dynamic DNS to access the PCs on their internal VPN ...
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3answers
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How WANs work and why it is it bad to run DNS and DHCP on a router?

I have some networking questions about isolating networks and why it's bad to run DHCP and DNS on a router and should be run on a server. Question 1: What is the purpose of the WAN interface and how ...
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3answers
64 views

ACL for DNS clarification

I do not understand why the second ACL is needed if all I want is to ensure all networks use a certain DNS server (for example 192.0.2.1) access-list 112 permit udp any host 192.0.2.1 eq domain ...
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2answers
4k views

What is IP-over-DNS tunnelling?

What is IP-over-DNS tunnelling please? I have seen this term used in the context of a captive portal. The idea was to redirect clients to the local web server and to force the DNS (?). It was ...
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0answers
465 views

DNS not resolving through VPN [closed]

Looking for some help with our Office's VPN that I can't seem to solve... I am trying to remote desktop to the Work PC from Home PC via the DC ASA 5506-x VPN. I can only connect to the Work PC with ...
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1answer
406 views

Fortigate - Redirecting subdomains only?

I'm trying to figure out a way to have our Fortigate 60C redirect certain subdomains but not block complete access to the domain. E.G. I want to block update.microsoft.com but I don't want microsoft....
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230 views

Cisco IP SLA HTTP request with frontdoor VRF

I am trying to use a IP SLA for HTTP on my Cisco ISR 4321 router to check if a website is reachable. The challenge is that I need to do that in a frontdoor VRF. I have configured ip name-server vrf ...
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2answers
342 views

How are packets routed based on IP and how are those routes acquired?

Good day all, this is my first question here, be gentle in judgement Background: At university, we are covering Network Routing Protocols. Having possibly found 2 issues with current routing ...
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1answer
226 views

How is a lost DNS query handled [closed]

If a DNS query gets lost along the way to its destination, is nothing done about it? In my networking class, my lecturer said that DNS runs on UDP. I verified this in Wireshark by doing nslookup for a ...
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2answers
810 views

Wireshark - capture all packets for HTTP request

I want to launch a HTTP request to a website I've never visited before. I would like to pick up all of the packets related to this request; so DNS packets, TCP packets, et cetera. Is there a way to ...
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3answers
918 views

connect a cisco router to the internet through a cable modem

The router gets an External IP address via DHCP from the Cable modem Clients inside the network get an IP address from Router's DHCP server I can ping that the external IP address from a client inside ...
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1answer
49 views

How do I find the IP of the DNS server that respond for a specific domain name?

So as the title says I want to get the IP of the DNS server that respond when I'm trying to reach a specific domain, using bash commands. If I understood it right, when I'm trying to reach www....
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1answer
60 views

Quanta switch not resolving addresses

I've got this brand new Quanta T3048. I've configured the VLANs we need but it came to my attention that the switch won't resolve any address even though I've set it (according to the configuration ...
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1answer
90 views

It's not showing the DNS why it is called reverse IP lookup?

I have searched a lot but I didn't get the reason that even after giving the IP address it never shows the DNS. If it doesn't give the DNS then why it is said to be reverse IP lookup?
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831 views

Why do I capture all DNS queries from everyone in the network when I port forward port 53 to my computer?

I'm seeing some things in Wireshark I can't explain. My setup is as follows: A router with a single global IP doing NAT for the devices behind it. I am also behind it with my computer. I port forward ...
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1answer
340 views

Access internal webserver with domainname points to external IP

We have a webserver on our LAN. Externally, we can use the public domainname (let's say business.com) to access the website. Internally, we need to use the local IP. We also want to use the public ...
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156 views

Different DNS resolution for same domain name [closed]

I am getting different DNS resolution for www.google.com. When I am using Google Public DNS i.e 8.8.8.8 then by using nslookup then it is giving IP address of Non-authoritative answer: Name: www....
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1answer
486 views

Can I ping a specific site without DNS server information? [closed]

If I clear DNS cache and remove DNS server information, how can I ping to a specific site?
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2answers
2k views

How to force users on my LAN to use a specific DNS server using ARP poisoning?

I'm attempting to force all hosts on my LAN to use a specific DNS server to filter certain material, however I'm running into problems. I've had problems in the past trying to configure my router's ...
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1answer
34 views

TZ205W DNS Issue

I have a firewall that is setup but need to have all users inside the network to use a preset dns server. While I know that I can set up this in the DHCP it does not stop a user from changing it in ...
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2answers
85 views

How can a public DNS server know the hostname of a machine on a private network [closed]

Example: a home LAN a simple SOHO router (both DHCP and DNS server at 192.168.1.1) 2 client machines (192.168.1.2 and 192.168.1.3) Is it possible for the Google public DNS server located at 8.8.8.8 (...
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1answer
84 views

Iterative queries of a default DNS server

I have just started to study networks and I have a confusion about what happens when a default DNS server does iterative queries to other DNS servers to resolve a name in an IP address. I am very ...
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1answer
224 views

How are IPv4 Addresses provided uniquely to domains?

this question has been bothering me for sometime and I've yet to receive a clear answer (it bothers me whenever I go to sleep). I would like to receive expert answers on this matter. Who mainly ...
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3answers
256 views

Can I see what happens when I run a DNS query?

My understanding is that when my computer wants to resolve a host name, it will ask the DHCP-assigned DNS servers first. If those don’t know, it goes and asks the ‘root servers’ who then defer to ...
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1answer
51 views

SRV Record for Service X [closed]

I've got a quite common question, which I can't find an answer for. Is it possible to create a SRV Record for any possible service I'm running? For example: I want webinterface.example.com to ...
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1answer
38 views

Is it possible to convert a public IP and port to a DNS? [closed]

Must be said, I'm a complete ignorant on these matters. Is there a way or service so I can take and IP address and its port and make it a DNS? Is it possible or am I doomed?. Thank you.
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1answer
67 views

WHOIS request with nodejs package failing [closed]

I'm trying to do a bulk whois lookup of around 7000 domains. I use the node js package whois. This worked while I tested with individual domains. After I made a bulk request for batch of 50 domins, ...
3
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1answer
174 views

rate-limit dns queries on HP procurve 8212zl

I had ast week the situation that a user accidentally got our DNS server to its knees by sending over 270K DNS queries to our dnsmasq. I was looking for a reliable method to prevent this Happening in ...
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1answer
573 views

Tracert getting timeout on second packet consistenly

I'm on a vpn and tracing to virtualmachines that live in the VPN Server. I've been experiencing slow queries, when they should be fast. below is what the trace is returning. I'm curious as to why the ...
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1answer
143 views

resolving IP address to FQDN effectively [closed]

We use Netflow to control traffic, when i want to resolve the IP addresses from netflow's outside destinations list, i get local google cache server's IP address, never the web sites that users has ...
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0answers
24 views

Should static IPs be set on the DNS/DHCP server, the host, or both? [closed]

Assuming a pretty regular business setup, when assigning static IPs for servers to use, should they be assigned on the DNS/DHCP server? Should they be configured individually on the hosts? Or should ...
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1answer
324 views

ASA as a local DNS resolver

I have an site to site VPN access configured by ASAs. My remote site needs to connect to the domain through the tunnel which will required DNS located on the main site. I would like to use DNS server ...
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3answers
7k views

Why is DNS an application layer protocol?

The main role of DNS is to translate Domain Names to their corresponding IP adresses, so why is necessary to be an application layer protocol? I think that DNS is an application layer protocol ...
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2answers
113 views

Is DNS geo-redundant if my traceroute to each NS shows the same location?

Some providers employ BGP anycast for their NS servers. As a user, when doing a traceroute, many may show an identical location for both servers, for a given client. When he.net used to anycast ...
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1answer
662 views

Is it possible to set up (geographic) anycast on the Internet?

The top level DNS-servers use geographic anycast. Is it possible to set up geographic anycast on your own (DNS) servers on the Internet? The top level DNS-servers use geographic anycast. Is this set ...