DNS Error: 193104 DNS type 'aaaa' lookup of [SERVERNAME] responded with code SERVFAIL

[GoWilkes]

I hosting client reported an issue to me today that she said has been happening for several days... possibly related to the issue I reported before from having a high number of Apache processes, but I don't know.

She uses Gmail for her email (and the Gmail website), and under Settings > Accounts and Import > Send mail as she's sending email through my server. She has the same settings that I use for my site, just with her email address instead of mine; port 465, using SSL.

Recently, when she tries to send an email she gets the following errors:

DNS Error: 193104 DNS type 'aaaa' lookup of [SERVERNAME] responded with code SERVFAIL

193104 DNS type 'a' lookup of [SERVERNAME] responded with code SERVFAIL , code: 0"

My Gmail works just fine going through my server, so I'm at a loss on what's up with this one. I tried creating a new email account on the server specifically for this, but that had the same error.

Any thoughts?

 

[GoWilkes]

Good news!! I found the issue, and I'm posting it here in case others are having the same problem.

A few days ago, Gmail had a significant amount of down time:

Google recovers from outage that took down YouTube, Gmail, and Snapchat

It appears that one user or another was continuously trying to access my server through Gmail, and it was failing. So I had this in my firewall's Permanent Deny list:

40.85.151.20 # lfd: (smtpauth) Failed SMTP AUTH login from 40.85.151.20 (US/United States/-): 5 in the last 300 secs

And this IP is in the range of those owned by Gmail:

Whois-RWS

I removed it from the Permanent Deny list, and voila! No more problem

So if you're having a similar problem, be sure to check your firewall to make sure one of Gmail's IPs aren't being blocked.

 

[cPanelLauren]

Hi @GoWilkes

I'm happy to hear you identified the source of the issue and thank you very much for posting the resolution to it here!

 

[GoWilkes]

The problem has actually continued, and it's almost inexplicable. The client's Gmail is set up identical to mine, but it seems like every day she gets the same error. I poke at it and get it to work for a bit, then the next day... same problem.

What's mind-boggling is that I've logged in to her account on my computer, entered the exact same information as I have on my Gmail (same email and password for the "Send mail as" that I have for mine), and still... error. But it works fine when I log in to my Gmail account with identical information!

Today, the problem was "resolved" by adding all of these to the csf.ignore file in CSF (they were already in csf.allow):

209.85.128.0/17
64.233.160.0/19
72.14.192.0/18
74.125.0.0/16
172.217.0.0/16
40.112.0.0/13
40.120.0.0/14
40.124.0.0/16
40.125.0.0/17
40.74.0.0/15
40.76.0.0/14
40.80.0.0/12
40.96.0.0/12

If it's a firewall issue, though, I can't explain why it works with one Gmail account and not another.

If anyone can suggest more IPs that I should add that belong to Google / Gmail, I would appreciate it!