It seems that antivirus company AVG can’t get their DNS Setup right.
Today I spotted the below in syslog:
DNS format error from 204.193.144.47#53 resolving crashportal.avg.com/AAAA for client 127.0.0.1#34590: Name avg.com (SOA) not subdomain of zone crashportal.avg.com -- invalid response
So the AVG updater tried to contact via IPv6, as a record type of AAAA was requested, a host called crashportal.avg.com
. To do so it had to “resolve” that hostname crashportal.avg.com
to an IP address in order to submit a crash dump for a recent crash of their virus scanner (very trustworthy!), and the DNS resolver failed to resolve the IP address. So why is this?
Let’s see:
# dig -t AAAA crashportal.avg.com
; <<>> DiG 9.9.5-9-Debian <<>> -t AAAA crashportal.avg.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 21322
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
Huh? We can’t resolve this because our server failed? Let’s see what’s going on…
# dig -t SOA avg.com
; <<>> DiG 9.9.5-9-Debian <<>> -t SOA avg.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42124
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 6, ADDITIONAL: 3
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;avg.com. IN SOA
;; ANSWER SECTION:
avg.com. 1160 IN SOA ns.grisoft.cz. domainadministration.avg.com. 2015061601 86400 3600 1209600 10800
;; AUTHORITY SECTION:
avg.com. 172607 IN NS a11-66.akam.net.
avg.com. 172607 IN NS a20-66.akam.net.
avg.com. 172607 IN NS a13-65.akam.net.
avg.com. 172607 IN NS a26-67.akam.net.
avg.com. 172607 IN NS a1-182.akam.net.
avg.com. 172607 IN NS a6-67.akam.net.
Ok, so the above quoted Akamai nameservers should be able to help… Let’s see:
# dig -t AAAA crashportal.avg.com @a11-66.akam.net.
; <<>> DiG 9.9.5-9-Debian <<>> -t AAAA crashportal.avg.com @a11-66.akam.net.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63788
;; flags: qr rd ad; QUERY: 1, ANSWER: 0, AUTHORITY: 3, ADDITIONAL: 4
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;crashportal.avg.com. IN AAAA
;; AUTHORITY SECTION:
crashportal.avg.com. 300 IN NS gtm-atl.avg.com.
crashportal.avg.com. 300 IN NS gtm-self.avg.com.
crashportal.avg.com. 300 IN NS gtm-tnt.avg.com.
;; ADDITIONAL SECTION:
gtm-atl.avg.com. 3000 IN A 204.193.144.47
gtm-tnt.avg.com. 3000 IN A 173.245.115.70
gtm-self.avg.com. 3000 IN A 212.96.161.252
So the server was not authoritative to answer the request and pointed us to a different set of servers
.
Note that the IP address from my error message (204.193.144.47
) belongs to one of the nameservers mentioned above!
Ok, let’s ask that server:
# dig -t AAAA crashportal.avg.com @204.193.144.47
; <<>> DiG 9.9.5-9-Debian <<>> -t AAAA crashportal.avg.com @204.193.144.47
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 47390
;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;crashportal.avg.com. IN AAAA
;; AUTHORITY SECTION:
avg.com. 60 IN SOA gtm-tnt.avg.com. hostmaster.gtm-tnt.avg.com. 2015052909 10800 3600 604800 60
Why does the nameserver respond with an SOA record even though it’s supposed to be authoritative and was asked for AAAA
? It’s not a delegation as — and this is exactly the error message — avg.com
is not a subdomain of crashportal.avg.com
. Duh!
In my humble opinion it is very disappointing if an IT security company cannot even get the basics right, such as DNS.
This issue reminded me of another similar issue I observed a while ago: Avira can’t get their DNS Setup right. And guess what? This was an antivirus company, too…