Tagdns

June 20, 2013

Weird mail problems today? Clear your DNS cache!

By laura

1 Min read

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20June

A number of sources are reporting this morning that there was a problem with some domains in the .com zone yesterday. These problems caused the DNS records of these domains to become corrupted. The records are now fixed. Some of the domains, however, had long TTLs. If a recursive resolver pulled the corrupted records, it could take up to 2 days for the new records to naturally age out. Folks can...

April 8, 2013

DNS, SERVFAIL, firewalls and Microsoft

By steve

6 Min read

3 comments

08April

When you look up a host name, a mailserver or anything else there are three types of reply you can get. The way they’re described varies from tool to tool, but they’re most commonly referred to using the messages dig returns – NXDOMAIN, NOERROR and SERVFAIL. NXDOMAIN is the simplest – it means that there’s no DNS record that matches your query (or any other query for...

April 2, 2013

Maybe the sky is only falling a little bit

By laura

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02April

There was quite a bit of breathless reporting last week about the DoS against Spamhaus and how it was large enough to break the Internet. As the postmortem has gone on, a few things are becoming clear. There was a lot of traffic, enough to swamp some major transit points. Most people, particularly in the US, saw no problems. Network engineers had more than a few sleepless nights trying to route...

March 28, 2013

Internet Storm Center on the Spamhaus DOS

By laura

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1 comment

28March

The Internet Storm Center (ISC) has a blog post up discussing the DOS attack against Spamhaus. They do confirm they saw traffic approaching 300Gbps against Spamhaus. They also point out that most people probably never knew. The attack was significant, but not globally so despite the media reports to the contrary. When news of the attack reached the Internet Storm Center, we did have a brief...

March 27, 2013

More on the attack against Spamhaus and how you can help

By laura

2 Min read

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27March

While much of the attack against Spamhaus has been mitigated and their services and websites are currently up, the attack is still ongoing.  This is the biggest denial of service attack in history, with as much as 300 gigabits per second hitting Spamhaus servers and their upstream links. This traffic is so massive, that it’s actually affecting the Internet and web surfers in some parts of...

December 12, 2012

Troubleshooting tools

By laura

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12December

There have been a number of comments on my post about Hotmail moving to SPF authentication having to do with troubleshooting authentication failures. I have been helping clients troubleshoot these issues, and am able to take on new clients to solve authentication problems. Contact me for more information. Of course, many of these issues can be solved with access to the right tools. Steve’s...

November 20, 2012

Collaboration key to fighting crime on the internet

By laura

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20November

The Pittsburg Post Gazette has a good article on the DNS Changer Working group and how it can serve as a model for future collaboration against cyber crime.

October 29, 2012

MAAWG presents the first J.D. Falk award

By laura

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29October

Last week at MAAWG went much like all MAAWG conferences go: too much to do, too many interesting panels to attend, too many people to connect and work with, a plethora of very interesting keynote speakers and a total lack of sleep. Most of what happens at MAAWG is not public, but some of the events are. One of the things that I can talk about is the J.D. Falk award. This award was established by...

October 22, 2012

Setting up DNS for sending email

By steve

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22October

Email – and email filtering – makes a lot of use of DNS, and it’s fairly easy to miss something. Here are a few checklists to help: Data you need before you start: [table] Information,for example Return path / bounce address,bounces.myesp.com Mailserver hostname,mail4.myesp.com Mailserver external address,192.0.2.4 DKIM “d=”,greatbigmarketer.com DKIM selector,oct2012...

February 24, 2012

So you want to start a company? (part 4)

By steve

4 Min read

4 comments

24February

You’re setting up a company (or a new division or maybe even a new brand) and you’d like to use email to communicate with your customers. In this series of posts I’m going to touch on some of the things you can do today to make email life easier for you in the future. Today’s final post is on DNS hosting and setup. 5. DNS hosting DNS is what lets you actually use the domain you’ve...