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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Do domains frequently change their IP addresses

I have the domain of some organization that requests my site too much. I want to restrict their access - but how? We only have the domain of the requester sfasu.edu . The QA of our team is using tool ...
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13 views

Web server, firewall and active directory: internal network connection error “DNS rebinding attack” [closed]

I have a problem with a web server (WS) (apache on ubuntu 20.04 server), Fortinet Firewall (FF) and windows Active Directory (AD). My ISP recently upgraded my Internet connection and changed some ...
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11 views

Large volume of none.domainname.local dns queries [closed]

I hope this finds the community members and their loved ones safe and healthy. 1. Network layout and details: A. I have a Pi-hole running DNS recursive server using Unbound (version 1.9.4) on a ...
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0answers
16 views

My web-app works when visited without a www prefixed to its domain, but it returns a 522 error when visited with a www prefix [closed]

I am hosting a simple web-app on Cloudflare using pages and a basic DNS configuration for a custom domain name. For privacy sake, call it myapp. When I visit https://myapp.com the web-app works ...
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31 views

Cisco DHCP using dynamic updates

I would like to use a configuration on a Cisco router that allows for clients to resolve the names of other clients without the use of mDNS. I have following configuration: roTST01#show running-config ...
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2answers
24 views

Packet Tracer - PING from CLI of router to website

I am currently sending a PING from a Router2 of the Network shown bellow. By using the CLI commands I'm trying to do it in 2 different ways: PING + IP 192.168.1.9. As a result, it succeeds. PING + ...
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2answers
43 views

How do machines setup a route in a network?

So I have been reading a bit about networking, and I am a bit confused about what exactly happens after domain name resolutions. Lets say I do a get request to "some.website.com". First, my ...
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0answers
29 views

What is a CNAME and what are some of its benefits? [closed]

What is a CNAME and what are some of its benefits? For example, how does it differ from A & AAAA records?
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1answer
34 views

Why can't I access Whitehouse.Gov with the IP address or the Aliases? [closed]

I'm studying the basics of networking at the moment, and I was testing out what I had learned when I discovered that I could not access WhiteHouse.gov via the IP address. After using dig on WhiteHouse....
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1answer
12 views

What is the significance of configure TTL value while creating A record and AAAA Record in External DNS [closed]

Is Time to live (TTL) value has any impact on DNS querry . Because in our external DNS we generally set TTL value to 1 hours and some times 5 minutes while creating A records and AAAA records in ...
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1answer
206 views

Why DNS services Like google public DNS and Cloudflare 1.1.1.1 has ipv6 versions?

I understand the need for ipv6 as we ran out of ipv4 but dns resolvers like google and cloudflare already have ipv4 addresses for resolving dns and i don't see compatibility as a reason either because ...
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1answer
47 views

How is traceroute able to display hostnames?

When performing a traceroute, what function on the ISP gateway is advertising the hostname? When we traceroute to Google.com for instance; Tracing route to google.com [216.58.213.14] over a maximum of ...
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2answers
26 views

What's the meaning of requests in Load-balancer?

When I read thisarticle: there is a term: Load-balancer is the piece of hardware that listens on a particular IP address and forwards the requests to other servers. Major sites will typically use ...
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13 views

Cisco RV345P - disable DNS names for DHCP bindings

This is about Cisco RV345P router (non-IOS, it's the Web interface kind). When the hosts on our office LAN obtain address from DHCP their host name is automatically registered in a local DNS resolver ...
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1answer
17 views

DNS request on google.com. with QTYPE = 0xff returns no entries [closed]

Ive written my own DNS request client but I'm having some interesting behavior. If I send the request with the QTYPE section = 0xff, I get a valid response however with no entries. My Request: 0x70 ...
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1answer
47 views

How do I know when an AAAA record is required? [closed]

I'm trying to wrap my head around DNS. My biggest issue right now is understanding when an AAAA record is required. Recently, I was asked by a colleague to point a subdomain from Server A to Server B....
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1answer
16 views

Will DNS TTL impact Browser’s HTTP Cache? [closed]

Browsers are known to cache HTTP resources to save bandwidth and improve performance. I’m not 100% sure about how HTTP cache works in web browsers but I can see sometimes that an object with “cache-...
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1answer
58 views

What is the purpose of Cisco's `ip domain round-robin` feature?

While configuring one of Cisco's routers and reading documentation I've found an interesting feature: ip domain round-robin. Documentation says, that this options makes dns server rotate entries ...
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2answers
217 views

Can Cisco Config cause Unidentified Network

I have a Cisco C9300-24P layer 2 switch with a dozen computers and 2 servers on the same VLAN, all statically set with no default gateway as there is no router and all offline from the internet. The ...
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2answers
46 views

If you have multiple domains pointing to the same IP address, can you see which domain a packet was sent to? [closed]

If you have multiple domains pointing to the same IP address, can you see which domain a packet was sent to?
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2answers
69 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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2answers
673 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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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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2answers
55 views

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
167 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
416 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
75 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
108 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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1answer
629 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
243 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
264 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
38 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
150 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
242 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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0answers
635 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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0answers
336 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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1answer
658 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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4answers
2k 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
63 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
66 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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2answers
137 views

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

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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2answers
1k 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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0answers
208 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
958 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
4k 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
36 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
98 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
91 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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4answers
315 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 ...
0
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1answer
58 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 ...