Questions tagged [reverse-dns]

Reverse DNS lookup is the determination of a domain name that is associated with a given IP address using the Domain Name System (DNS) of the Internet.

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5 answers
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Reverse DNS - how to correctly configure for SMTP delivery

I started a new service and we need to send emails to our customers (new account confirms, etc). My server is known as prod01.bidrodeo.com and resolves to 97.107.134.38 . For reverse DNS, 97.107....
Krystian Cybulski's user avatar
28 votes
1 answer
6k views

Do internet standards require reverse DNS for every device?

The requirements surrounding reverse DNS are confusing! People frequently talk about everything breaking if reverse DNS is not present, and that sounds scary. Even in cases where applications don't ...
Andrew B's user avatar
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26 votes
4 answers
22k views

Reverse DNS in a CIDR world

Reverse DNS seems to be strongly tied to class boundaries, what methods exist now that CIDR is the standard to delegate authority for a subnet? If multiple methods exist which one is best? Do you ...
Zoredache's user avatar
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36 votes
6 answers
61k views

Multiple Reverse DNS Entries?

I'm a DNS noob, so here's a question: Can a server have multiple reverse DNS entries? Or does one IP address just resolve to one DNS name? Here is why I need this: I have a number of sites hosted ...
Sam Schutte's user avatar
9 votes
4 answers
20k views

How does a Reverse DNS lookup work with regards to spam filters?

I have heard that most spam filters use a reverse DNS lookup on the originating IP address of the sending SMTP server (or something like that) as part of the verification process. I want to make sure ...
codeflunky's user avatar
19 votes
2 answers
28k views

PTR record (rDNS) for multiple domains on a shared IP address

I host multiple domains on a single IP address: cats.com A @ --> 10.20.30.40 A mail --> 10.20.30.40 MX @ --> mail dogs.com A @ --> 10.20.30.40 A mail --> 10.20.30.40 MX @ --> ...
dbasch's user avatar
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12 votes
3 answers
3k views

What is reverse DNS?

I've lot of *.in-addr.arpa domains requests in my OpenDNS account. I know this should be normal and it's about reverse DNS. I've been reading here and there but still I can't really get how it works ...
Pitto's user avatar
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10 votes
3 answers
19k views

Is it bad to have the reverse DNS for two IPs point to the same domain name?

I am in the process of setting up a new server for my web application (the site will be moved, it is not for load balancing or the like), which has a different IP address from my existing server. My ...
Daniel Vandersluis's user avatar
9 votes
5 answers
11k views

How important are PTR records for Email Servers?

Does anyone know of any studies done to show how much email will be rejected if there is not ptr record for the SMTP banner name of an email server? Are reverse checks always done when enabled, or ...
Kyle Brandt's user avatar
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7 votes
2 answers
12k views

sshd warning, "POSSIBLE BREAK-IN ATTEMPT!" for failed reverse DNS

Whenever I SSH somewhere I get something like this in the logs: sshd[16734]: reverse mapping checking getaddrinfo for 1.2.3.4.crummyisp.net [1.2.3.4] failed - POSSIBLE BREAK-IN ATTEMPT! And it ...
rking's user avatar
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3 votes
1 answer
13k views

Reverse DNS Lookup from the Command Line

I'd like to get a list of all domains pointed to a certain IP address. Is there a way to get this information from the command line? Nothing like "host", "nslookup" or "dig -x". Those return the ...
nowthatsamatt's user avatar
21 votes
5 answers
3k views

Is it good practice or too draconian to reject mails from mailservers with no RDNS

I've recently dropped SpamAssassin and am now basing spam rejection on DNSRBL's, grey-listing and other basic tests and I'm wondering whether I should also block hosts that don't have a valid RDNS ...
Peter White's user avatar
11 votes
5 answers
10k views

Apache httpd won't stop doing reverse DNS requests for clients' IPs

Obviously my Apache httpd instance is doing reverse DNS (RDNS, give me the hostname for this IP address) lookups for each incoming client connection's IP address. This is bad. Especially since ...
Paul's user avatar
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10 votes
1 answer
10k views

Remote connection to MySQL server takes very long

I have a MySQL 5.0.75 server running on my Linux notebook to which I want to connect from another machine in the local network. This connection takes 5-6 seconds: mysql -h 172.22.65.101 -u myuser -...
Lennart's user avatar
  • 203
7 votes
6 answers
11k views

Finding all domain names that resolve to the same ip?

Lately I've been tracking a spammer on craigslist. I recently discovered that he's added a new technique to his arsenal, he registered a whole bunch of domain names but they all resolve to the same ip ...
Janak's user avatar
  • 264
6 votes
3 answers
9k views

SMTP host name vs. domain in "From:" address vis-a-vis Email Deliverability

I'm trying to implement (or make sure that I'm correctly following) email sending best practices to improve deliverability, but the role of the smtp server's host name vs the domain name of the From: ...
Jared Duncan's user avatar
4 votes
2 answers
28k views

How do I set up a reverse zone file?

I have this zone file in bind: $TTL 86400 mysite.net. IN SOA ns1.mysite.net. admin.mysite.net. ( 2006012008 86400 3600 604800 86400 ) ...
lillolollo's user avatar
4 votes
2 answers
359 views

setting the reverse dns for a email server

'm having some trouble with email on a dedicated server, with Windows Server 2008. I've reached the conclusion I have to setup reverse dns for the mail server. The current setup is this: The mail ...
Tudor Carean's user avatar
2 votes
1 answer
948 views

Wildcard DNS like "*-test.example.com"

Is it possible to set up a wildcard domain like "*-test.example.com"? The main reason I'm asking is because I'm in the process of setting up Continuous Integration with Jenkins, and we'd like to ...
Sean Hagen's user avatar
1 vote
1 answer
534 views

Where did dedicated.abac.net. come from in my rDNS and PTR records?

So I followed this guide to the letter: http://docs.cpanel.net/twiki/bin/view/AllDocumentation/WHMDocs/RdnsForBind I did so for 3 domains. When I "test" the records and enter: host 64.150.176.81 on ...
darkAsPitch's user avatar
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1 vote
2 answers
2k views

How to append a domain to a PTR resolution?

I have a bind9 server authoritative for my domain example.com. Forward resolution works, PTRs as well up to a point. I currently have 254.10.10 IN PTR srv. in my PTR zone for 10.x, which ...
WoJ's user avatar
  • 3,657
127 votes
15 answers
160k views

What's the reverse DNS command line utility?

What's the command to find the name of a computer given its IP address? I always forget what this command is, but I know it exists in Windows and I assume it exists on the *nix command-line.
Peter Turner's user avatar
  • 2,278
11 votes
4 answers
88k views

How to setup PTR (Reverse DNS) at Godaddy DNS manager

My hosting provider already did PTR setup. Now i have to setup it at my DNS holder i guess. What am i supposed to do at my Godaddy account. thank you. my ip : 64.250.113.235 and you can check my ptr ...
Furkan Gözükara's user avatar
10 votes
4 answers
36k views

Reverse DNS Setup for an IP with multiple domains

I am trying to clarify my Reverse DNS PTR lookup for a domain. I have a server with a single IP addresses and multiple accounts, all sharing that IP address; My PTR is currently: 24.210.31.in-addr....
Martin's user avatar
  • 217
7 votes
3 answers
21k views

how to add a REverse PTR Record on Amazon Route 53?

if i have the below ip 168.144.254.X and i would like to add a ptr record in amazon in the form of X.254.144.168.in-addr.arpa what should be in the name field and what should be in the value field ...
Oscar Cabrero's user avatar
7 votes
6 answers
13k views

How do I change reverse DNS on Google Cloud Compute?

How do I change reverse DNS on Google Cloud Compute? I want to add reverse DNS to Google Cloud Compute and can't figure out howto do it. I want to map 11.97.196.104.bc.googleusercontent.com to ns1....
Surjit Sidhu's user avatar
7 votes
1 answer
13k views

Reverse DNS is not a valid Hostname error from MXToolBox

I can't send email messages from my server. However, I can receive email messages. I set up my server the exact same way I did many times which I've proven it works and it's pretty straightforward and ...
Jason Lint's user avatar
6 votes
3 answers
16k views

How to configure bind9 to be a local DNS only with no internet access?

I want to configure bind9 to be a local DNS only with no internet access at all. So I have 5 PCs in my virtual domain xy.com. Within this domain there is no access to the internet. The DNS server ...
JohnnyFromBF's user avatar
  • 1,259
5 votes
2 answers
16k views

Do I need to Set-up PTR record in SPF Setting?

I have set-up the RDNS from my hosting provider for the ip address to resolve to "maximus.example.com". After that, do I also need to add the PTR records to the SPF Text details in my DNS zone file as ...
Neel's user avatar
  • 1,471
5 votes
3 answers
17k views

How do you configure BIND to forward reverse DNS queries to another DNS server?

I've got 2 domains in my environment. One of them is an active directory domain for 'myproductionlab.local' at 10.60.0.0/16 Then I have a debian box running bind9 for a domain, 'mytestlab.local' I ...
parsecpython's user avatar
5 votes
2 answers
43k views

Why SMTP Reverse DNS Mismatch Reverse DNS does not match SMTP Banner?

I have set rDNS to mail.simplyislam.biz for IP 178.32.48.104 with my hosting server and also in DNS control panel. However, I am still failing this test Result: SMTP Reverse DNS Mismatch Warning - ...
atifdarr's user avatar
4 votes
5 answers
43k views

How do I configure reverse DNS for a SMTP server [duplicate]

We use iis 6 to send out emails for our website but some email addresses bouce backs. It only appears to be 2 addresses. There is at least 100 different email addresses sent to at the same time as ...
user avatar
4 votes
2 answers
16k views

Delivered to internal network by a host with no rDNS

Recently our emails started going to spam for recipients at Gmail and Yahoo mail. I ran a SpamAssassin test, and have found the following: pts rule name description 0.0 ...
user3521621's user avatar
4 votes
1 answer
7k views

Hotmail/Outlook dumping apparently valid emails

I've written some software that operates a non-commerical contact list for clubs, where the server sends out admin mails to the entire club. The emails are received Ok on Yahoo, gmail, and AOL, but ...
EML's user avatar
  • 460
4 votes
2 answers
598 views

Slow connect on ssh on Ubuntu

I've recently installed Ubuntu 10.10 as a second OS on my desktop, but I'm having a strange problem: it takes several tens of seconds to connect to other linux machines via ssh. On Windows, I have no ...
evilpenguin's user avatar
4 votes
4 answers
12k views

How do you know if reverse dns is setup correctly on your server

Total newb question I know, but I just want to be sure.
trustfundbaby's user avatar
3 votes
3 answers
1k views

DNS, should I be using A instead of CNAME?

I'm doing a big reshuffle of our websites and hosting, moving about 10 domains to a new server. In doing so I had to make some changes to the DNS, pointing all of the domains at the new server. ...
Ben Everard's user avatar
2 votes
4 answers
420 views

Does sending e-mail in the name of customers increase the risk of being marked as spammer?

We are developing a SaaS website application that lets users send invoices to their clients. Ideally, these e-mails should appear to be originating from our customers, so the sender e-mail address ...
Adrian Grigore's user avatar
2 votes
2 answers
3k views

ISPs and reverse DNS lookups

I read in easyDNS that, in order to set up reverse DNS, "The IP block must be delegated to our nameservers by your ISP." Is that always the case? What if you decide to host your name servers? Will ...
ezequiel-garzon's user avatar
1 vote
3 answers
11k views

Reverse DNS does not match SMTP Banner [duplicate]

I'm new to this site but I have found many good answers on this site before. I have also searched for my actual question but I didn't found the answer or at least I didn't understand what should I do ...
SLyn's user avatar
  • 13
1 vote
0 answers
465 views

Domain whitelisting in Kubernetes DNS Service

Can I use Kubernetes dns service to whitelist the domains for my pods? I want to restrict the outgoing (egress) calls using Kubernetes dns service. if I can achieve this, can someone let me know the ...
solveit's user avatar
  • 265
1 vote
1 answer
607 views

Postfix/Spamassassin can't determine rDNS too often

I am running a Debian 7.9 server with Postfix 2.9.6 and Spamassassin 3.3.2. One of the standard checks Spamassassin does, is to check for a rDNS record. I am assuming that it gets that info from the ...
comfreak's user avatar
  • 1,531
1 vote
1 answer
1k views

Reverse dns for web/mail server with single ip

I have a single server with single ip running a web server, mail server and bind (all for a single domain). In my DNS zone file I created A records for www.domain.com, mail.domain.com, ns.domain.com ...
user1583209's user avatar
1 vote
3 answers
10k views

Hotmail wants me to modify my SPF record

This is my current SPF record. It works well with gmail and yahoo but hotmail was ignoring. So i used their submit system and now they replied me with the text below. This is my current spf v=spf1 a ...
Furkan Gözükara's user avatar
0 votes
1 answer
466 views

Why create a reverse DNS record for every device that connects to a wireless network?

There's this network I connect to often. After some experimentation, I figured out that when you connect to the network, the DHCP server assigns you an FQDN that usually follows the scheme <your-...
kimbo's user avatar
  • 63
0 votes
1 answer
3k views

Reverse PTR record lookup not working with dig

As mentioned here, having a Reverse PTR record is key for successful email sending and delivery from one's own server. In order to check if it's correctly set for my server, I tried: dig -x 111.111....
Basj's user avatar
  • 739
0 votes
1 answer
2k views

Reverse DNS record can't point to Domain name but it can point to IP [closed]

I am using parallels plesk for hosting my websites, Some days ago I tried to send emails from my mail server and the mails were going to spam,So i tried spam assassin to detect whats wrong. Here is ...
Vedant Terkar's user avatar
0 votes
2 answers
2k views

rDNS 'zone [xxx] has no address record (A or AAAA)

teaching myself some server tricks. Getting trouble with bind9 on debian8. named-checkzone pro.lan db.pro.lan.inv zone pro.lan/IN: NS 'server.pro.lan' has no address records (A or AAAA) my db.pro....
Ragnar's user avatar
  • 113
0 votes
1 answer
375 views

Reverse DNS issue with Mailserver (Postfix) [duplicate]

My mail server is set to server.mailtuner.com, but when i try sending to a hotmail user, it goes into the spam folder. Results on mailtester show the following reverse DNS issue: https://www.mail-...
frederic abdou's user avatar
0 votes
2 answers
320 views

Some advise needed on how to setup reverse PTR on web and mail server

I'd appreciate some advise on how to run DNS with both httpd and mail running on the same server. I have one server running on AWS, and i want to run both httpd and mail on it. Currently it just runs ...
ATv's user avatar
  • 129