DNS & network news

Monthly Archive: June 2019

Spf record has too many DNS lookups

Hi, I’ve moved the company I work for over the GSuite from another mail service. I’ve added Google as a include statement to the spf txt record along with another include statement for a service that is generating the email signatures.

If I use GSuite Tool box Mx checker it says I have too many DNS lookups. Other Mx spf checkers on the internet don’t report this problem.

I believe that all the IP ranges in the spf are required, is there an approach to shortening it?

submitted by /u/boltos1
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Anyone have a list of any other anycast servers for the public.

Title says it all: I want to know are there any other any cast servers that are for the public that are outside of the one’s I know of I included in the list DNS servers known by me below:

4.2.2.1

4.2.2.2

4.2.2.3

4.2.2.4

4.2.2.5

4.2.2.6

209.244.0.4

209.244.0.3

208.67.222.222

208.67.220.220

208.67.222.220

208.67.220.222

1.1.1.1

1.0.0.1

8.8.8.8

8.8.4.4

9.9.9.9

149.112.112.112

74.82.42.42

submitted by /u/ihoman202
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DNS corruption issue

I have an issue where my DNS responses get corrupted when they reach my TCP/IP stack. This is what’s happening:

I have Wireshark running listening for DNS traffic on my NIC.

I dig slack.com on 1.1.1.1

dig @1.1.1.1 slack.com

Wireshark gives me this response:

114 23.277504 192.168.1.142 1.1.1.1 DNS 80 Standard query 0x921b A slack.com OPT

123 23.278722 1.1.1.1 192.168.1.142 DNS 1049 Standard query response 0x921b A slack.com A 13.249.2.166

However, dig gives me the following response:

;; Warning: Message parser reports malformed message packet.

; <<>> DiG 9.10.6 <<>> @1.1.1.1 slack.com

; (1 server found)

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37403

;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; WARNING: Message has 12795 extra bytes at end

;; QUESTION SECTION:

;slack.com. IN A

;; ANSWER SECTION:slack.com. 30770 RESERVED0 A # 4 0DF902A6

;; Query time: 1 msec

;; SERVER:
1.1.1.1#53(1.1.1.1))

;; WHEN: Tue Jun 18 14:28:42 CEST 2019

;; MSG SIZE rcvd: 12847

So the DNS response arrives correctly at my NIC, but not at the console/browser/application/wherever i want to use this response.

I've tried different upstream DNS servers, local DNS server (dnsmasq), all the same response.

When i use a VPN, hence different networking stack, the response gets returned correctly. Also when i use my ISP's DNS i get correct responses.

I tried different NICs (Belkin USB, USB hub with Ethernet, Wifi), all with the same behavior.

I'm lost. Any ideas?

MacBook Pro 15" 2018 running MacOS 10.14.5

Wired connection to ISP router, no additional networking equipment.

DNS tried are 1.1.1.1, 8.8.8.8, 176.103.130.130, local dnsmasq.

submitted by /u/Toontje
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How do I conceptualize network protocols?

Not sure if this is where to post this but I’ve been studying IT for a while not but I’m still trying to wrap my head around a core thing.

Basically, I’m trying to conceptualize network protocols since they make up a backbone of everything Internet/IT.

I think well in metaphors so comparing it to traffic infrastructure where data is people and packets are cars or biology where data is dna and packets are cells traveling through the blood stream… basically, I get that 1s and 0s are the base components. And packets are made up of those and it goes up from there. Routers, copper wires, and radio signals, etc, are the medium in which they travel.

How/where do protocols fit in? Are they even a “physical” component? Or more of just an idea? An abstraction?

Hope this makes sense. And any help is appreciated.

submitted by /u/bluehood380
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