DNS & network news

Monthly Archive: December 2016

Correct config for smartphone app DNS

Hi everyone, I have an odd problem.

I have the following landscape.

domain.com, www.domain.com -> A record points to some other host qa.domain.com -> A record points to an AWS server

Now here’s what’s going on. If you go to qa.domain.com, it goes to the AWS server.

If you go to qa.domain.com/api/something.php, it is supposed to go to the AWS server, but sometimes, it gives a 404 error from the hosting provider. I can’t make any sense of it.

The variable is my geography or my wifi/cell network. For instance, from my Sprint hotspot, all the requests are always answered by the AWS server whereas my home wifi will have qa.domain.com work correctly whereas qa.domain.com/api/something.php will give a 404 error from the hosting provider.

I’ve tested this around the country and I see this off and on.

But I don’t even know where to start because the A record config works most of the time. Why does it sometimes result in a 404 from the hosting provider when on the same time as the failure, simply trying to reach qa.domain.com does result in the request going to the AWS?

submitted by /u/zantosh
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Ping works by IP but not hostname even though it is resolving the correct IP

I’m having the weirdest issue here and I’m hoping that someone here can tell me whether it’s DNS related or if I’m just barking up the wrong tree.

I recently implemented a DNAME on my Windows Server 2008 R2 DNS box to point to forcesafesearch.google.com for the zone www.google.com. Ever since then people are having intermittent connection issues to all sites, not just Google. I’ve verified that none of the updates listed in the comments of this post are installed.(https://www.reddit.com/r/dns/comments/4fi6gu/force_safe_search_google_search_with_dns_not/). I’ve also blocked UDP access to ports 80 and 443 to prevent googles QUIC protocol from messing with me but that didn’t help either.

Here is the weird part though. When I ping www.google.com it resolves the safesearch.google.com name and proper IP in the request, but it will time out. If I then take that IP and ping it directly it works fine. Am I missing something in the way that the ping command works? Is this even a DNS issue at all?

Thanks in advance for anyone who may be able to help.

C:Usersuser>ping www.google.com

Pinging forcesafesearch.google.com [216.239.38.120] with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out.

Ping statistics for 216.239.38.120: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

C:Usersuser>ping 216.239.38.120

Pinging 216.239.38.120 with 32 bytes of data: Reply from 216.239.38.120: bytes=32 time=15ms TTL=56 Reply from 216.239.38.120: bytes=32 time=15ms TTL=56 Reply from 216.239.38.120: bytes=32 time=15ms TTL=56 Reply from 216.239.38.120: bytes=32 time=15ms TTL=56

Ping statistics for 216.239.38.120: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 15ms, Maximum = 15ms, Average = 15ms

submitted by /u/Nife_Wrench
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Google's DNS entries are creepy

Hi,

tonight I scripted a little bit of a my new Java project. In this project I need to resolve DNS entries, so I wrote some lines of code for resolving any kind of DNS record. As I guessed I’m finished, I run the code against some domains to see all their DNS records. I started with reddit.com, youtube.com and it worked very well. Then I queried google.com, the tool crashed.

At this moment, I wondered why it didn’t work as expected, but on every other domain it worked. As a result, I enabled some debugging options to see some raw data.

And there it was.I matched every DNS record type as described in RFC 1035 to an ENUM. Google uses another type. They use the DNS type 257 with the value [B@8efb846 First, I guessed they did the CAA-Record wrong, but the value format doesn’t fit.

So what is Google doing there? Do you have an answer guys?

submitted by /u/chrros95
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Anycast with AD?

We have a fairly large Enterprise in which we are redesigning the WAN from a single Internet egress to a regional peering concept. I would like to have our Systems Engineering folks look at Anycast DNS in order to leverage closest egress point out of our corporate network as well as to Internet resources. I mentioned Anycast DNS and they asked why we weren’t considering Active Directory and global catalog.

Does Microsoft support Anycast DNS within AD?

submitted by /u/UDP4789
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how do I configure my A record for mail AND website so www works as well?

Hi guys, our company is busy with a few new websites. Since a office365 for every website is a huge overkill for now, we use a hosting package from our hoster.

Current setup:

@ TTL1 A (1.2.3.4 MAIL) @ TTL1 AAA (IPV6 ADR FOR MAIL) @ TTL1 MX (10.mx.email.) @ TTL1 (SPF Record TXT) autoconfig TTL1 (CNAME) autdiscover TTL1 (CNAME) www TTL1 (5.6.7.8 Website)

This config doesn’t allow connecting to the website without www. since I can’t have 2 A records with @, how can I make sure the mail works, and people are able to connect to the website without www? thanks in advance guys!

submitted by /u/BMWHead
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Is it possible to get hostname from ip not by using PTR records?

I’m not sure this is the right place to ask this question, if not please refer me to the right place.

For many websites on the internet (for example reddit), there is no PTR record in the dns server, so I cant get the hostname using the ip address. however I can get the ip address using the the hostname. Is there a way to look for host name not with PTR records, but by looking at the data of the A records? or in some other way? So basically what i’m asking is, how can I get the hostname from ip when the simple nslookup IP does not work?

submitted by /u/moshe7007
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