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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11
votes
3answers
2k views

How are the hosts in the tracert 216.81.59.173 able to use random domain names? [closed]

How are the host names in this trace route able to use random top level domains? I didn't know there was an 'Empire' or 'victory' top level domain. C:\Users\Chloe> tracert 216.81.59.173 Tracing ...
11
votes
2answers
5k views

Cisco ASA double NAT with DNS translation

I'm trying to set up double Auto NAT with DNS translation on Cisco ASA 9.0(3), and I'm having a few challenges with the DNS portion. I got double NAT working correctly, such that I have a server in ...
10
votes
1answer
6k views

Cisco IOS Forward / reverse name lookups

I want to configure our Ciscos so they can do forward DNS resolution, but not reverse DNS resolution from the CLI. R01(config)#ip domain-name domain.local R01(config)#ip name-server 10.1.1.1 R01(...
7
votes
1answer
3k views

DNS Doctoring / Reply Modification on Cisco 1900 series ISR

We have a Cisco 1900 ISR and have recently setup a web-server at ourdomain.com. The site works perfectly, however from the LAN we cannot use ourdomain.com to access the site, instead everyone has to ...
6
votes
3answers
4k 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 ...
6
votes
1answer
3k views

DNS options Ironport Web security appliance

I'm running a Ironport WSA in transparent mode. In advanced proxy config - DNS Options I find the following: Find web server by: Specify how the appliance should find the location of the requested ...
5
votes
1answer
2k views

Where is dns root server located? [closed]

I have some question regarding DNS root server. Where is it located ? In USA ? In europe ? Which company spends money to maintain dns root server ? What about fail-safety ? If root dns fails where ...
4
votes
2answers
1k views

Is it possible to get a listing of all DNS records that have a given CNAME? [closed]

Is there a way to get a listing of DNS records worldwide that contain a CNAME to a given domain, similar to how some sites provide a listing of domains related to a given IP address?
4
votes
1answer
213 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 ...
4
votes
2answers
9k views

Cisco ASA VPN with split-dns on a Windows VPN client

Split DNS ostensibly allows a remote device accessing a LAN using VPN to direct DNS queries for internal domain names to internal DNS servers while queries for public domain names are directed to ...
4
votes
3answers
467 views

Cannot access certain web page. Ping succeded traceroute didn't

This is my first question on forums at all. I work as a network support engineer and I have a little issue at work and I would really appreciate advice from you. Cannot access the url www.reach2.org ...
4
votes
1answer
691 views

Why do some AAAA records behave strangely on existing A records?

I noticed the following odd behavior with AAAA records when querying existing A records. By base domains I mean domain names without subdomains. So when an A record exist and an AAAA record does not ...
4
votes
2answers
2k views

Host IPv6-only website and allow access to IPv4-only clients

Lets say site.example.com runs only with AAAA records, and I wish to access that site from IPv4-only network, and I don't want to do tunneling neither other protocols that masquerades IPv4 over IPv6 ...
4
votes
1answer
141 views

Copying bytes from Wireshark

Should it be possible for someone to export the binary payload (say from a UDP packet) captured from Wireshark and later send this stream as a "valid" UDP packet? Longer story: I've captured a DNS ...
4
votes
2answers
785 views

DNS/domain not working on cisco pix 515e

I was able to pick up a pix515e for my home network, I've got it running Version 8.0(4)28 and Device manager version 6.1(3) which I think are the latest that it will support with its 64Ram/16Flash. ...
3
votes
3answers
213 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 ...
3
votes
2answers
248 views

Is Reverse DNS part of the DNS protocol? [closed]

Is reverse DNS part of the DNS protocol, i.e. part of the official DNS specification? Is reverse DNS managed by standard DNS servers and a type of request that DNS servers understand and respond to, ...
3
votes
2answers
3k 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 ...
3
votes
2answers
5k views

ASA as DNS transparent proxy

I'm trying to configure an ASA as transparent DNS proxy. This means that the ASA has to redirect all the DNS queries that violets a certain policy to a DNS server. For example in this way it is ...
3
votes
3answers
8k views

Why can't I do a reverse DNS lookup on this IP address? [closed]

I keep noticing that web pages I have open are exchanging messages with third party servers without my permission. This is somewhat annoying, and I would like to find out which pages they are so I ...
3
votes
1answer
767 views

Router equipment and interface info in reverse DNS

Question about pages 17 and 18, of 49, at http://www.nanog.org/meetings/nanog45/presentations/Sunday/RAS_traceroute_N45.pdf It is mentioned that prefixes and numbers in DNS (when doing traceroute) ...
3
votes
1answer
1k views

Forcing Cisco DNS relay to send requests from behind PAT [closed]

I have a Cisco 1811 configured with PAT: interface FastEthernet0 ip address dhcp ip nat outside interface Vlan1 ip address 192.168.0.1 255.255.255.0 ip nat inside ip nat inside source ...
3
votes
1answer
375 views

Who generates all the DNS requests when I plug my public IP router to the network?

When I plug my router with a public IP address on it into the network, I get discovered after few hours to days and become 'flooded' with DNS requests from many sources. Who generates these requests? ...
3
votes
3answers
1k views

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 ...
3
votes
3answers
3k views

DNS Resolution:<Backwards IP Address>.in-addr.arpa [closed]

Can somebody please explain whats going on here? localuser@localhost:~$ host 127.0.0.1 1.0.0.127.in-addr.arpa domain name pointer localhost. What's up with the IP address being resolved ...
3
votes
2answers
1k views

What is route 66 in the context of DNS?

There is route53 which in the context of AWS is their DNS service. However, I've heard the term "route66" on different occasions in the context of DNS, but it never made sense to me. I tried ...
3
votes
3answers
485 views

What exactly is a domain in context of DNS? [closed]

I am trying to understand the DNS. Say I have a domain named mydomain.com. And let's say that we have the following FQDNs: sub0.mydomain.com sub00.sub0.mydomain.com sub01.sub0.mydomain.com sub000....
3
votes
1answer
154 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 ...
3
votes
1answer
202 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 ...
2
votes
1answer
647 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 ...
2
votes
2answers
1k views

Choosing between BGP (AS Number) and Dynamic DNS

I have a client that provides an online API service that requires 100% uptime but has been facing connectivity challenges from ISPs. They started out with one ISP (ISP-A), who of course when there ...
2
votes
1answer
2k views

Why does a NS record need a domain name, not an IP address? [closed]

I'm a beginning learner of DNS. Some days ago I built a authoritative name server. Writing zone files, I had wondered why the right side of a NS record is specified not in an IP address but in a ...
2
votes
1answer
129 views

Juniper SSG Split DNS not working over tunnel

I am trying to get the DNS Proxy feature working in an SSG5 (Side B). The other side of the VPN is an SSG140 (Side A). The DNS server is on Side A. foo.com should send DNS queries to 192.168.1.2 (...
2
votes
2answers
859 views

Preferred anycast paths for DNS with Quagga BGP

Background and goal Am setting up high availability DNS servers based on Unbound. Both DNS servers has in reality twelve BGP sessions against different routers but to make this easier only one router ...
2
votes
1answer
341 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....
2
votes
1answer
2k views

Ping domain name using sourced interface

Problem: I want to be able to ping a domain name, sourcing from a particular interface on a Cisco router. Scenario: I have Router-A, an it has a management address of 1.1.1.1. I can only connect to ...
2
votes
1answer
689 views

DF bit always set for DNS query response

When I tried packet capture with wireshark, I observed that the Don't fragment bit is always set for 1. all TCP packets and 2. DNS query response. I understood why it is so in case 1, here Now, my ...
2
votes
1answer
143 views

Local DNS server + Firewall for reporting Setup

My problem is the firewall is only recording DNS requests from my local DNS server instead of the source computer. I would like to keep using my local DNS server with External DNS servers being the ...
2
votes
3answers
302 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 ...
2
votes
1answer
409 views

Serve a different server IP to clients based on locations

I am looking for a way to server clients a different IP based on location. I'm a Casper administrator (Mac management using software by JAMF Software) and manage over 75 distribution servers globally....
2
votes
2answers
61 views

Why does host+curl take longer than host alone and curl alone? [closed]

I tried to test the speed of my website, so I used time curl "http://google.com" The result ended with real 0m15.589s user 0m0.012s sys 0m0.000s I tried to see what took so long, so I timed ...
2
votes
1answer
10k views

Why does my router not reply to ARP requests? [closed]

I am trying to test the ability for an embedded system to create DNS requests and process their replies, but I'm having problems getting those replies. Physically, my embedded system (192.168.1.50) ...
1
vote
1answer
217 views

Why only 13 adresses for the DNS root zone [closed]

I know about anycasting and I know about the UDP limitation. Now, I was reading this article and it says the following (emphasis mine): Each IPv4 address requires 32 bytes. Accordingly, the ...
1
vote
1answer
44 views

Router decision making w.r.t web browsers

Two different websites have been opened from two different browsers(for instance chrome and firefox) on the same IP Device(PC) connected to the same router. When the response comes from far end, it's ...
1
vote
2answers
315 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 ...
1
vote
1answer
45 views

How do you check glue records if your ISP blocks access to the root servers? [closed]

Glue servers, apparently appear in the parent of the domain. How can these be queried, when for the last few months ISPs have been blocking access to the nameserver ports due to DoS attacks with ...
1
vote
1answer
67 views

DNS analytics solutions? [closed]

Something like http://netfee.ustc.edu.cn/dns/ Showing top DNS queries and top clients etc. I am not seeing any open source projects doing exactly the same thing, https://www.nanog.org/meetings/...
1
vote
1answer
35 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 ...
1
vote
1answer
123 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 ...
1
vote
2answers
850 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 ...