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prayagupa
Asked: 2014-07-24 10:18:11 +0800 CST

AWS - elastic load balancer unable to handle the request

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I'm totally new to AWS and the world. My problem here is while requesting to AWS server. I have a server staging-storage.zazzercode.co pointing to following DNS's with respective load balancers, 

s-storage-us-west-2-483191837.us-west-2.elb.amazonaws.com => s-storage-us-west-2
s-storage-us-east-1-1318227839.us-east-1.elb.amazonaws.com => s-storage-us-east-1

I live in Eastern world.

Point 0

I upgraded instance sizes from t1.micro to m3.medium hoping it would get fixed.

Point 1

While requesting to the server using hostname 'staging-storage.zazzercode.co', I get following error in a curl request,

curl: (6) Couldn't resolve host 'staging-storage.zazzercode.co'

According to man curl, 6 is, 

6      Couldn't resolve host. The given remote host was not resolved.

Point 2

It sometimes tells me 

HTTP/1.1 100 Continue

HTTP/1.1 504 Gateway Timeout
Content-length:0

Which is documented here - Troubleshooting Elastic Load Balancing: Error Messages suggesting

  1. Insufficient capacity in the Load Balancer to handle the request.(transient issue)
  2. instance closing the connection to ELB.

Point 3

It responds with proper response after few attempts. Others of my team face the same issue.

Point 4

When I ping the hostname, It hangs 

$ ping staging-storage.zazzercode.co
PING s-storage-us-west-2-483191837.us-west-2.elb.amazonaws.com (54.199.188.111) 56(84) bytes of data.

Point 5

I can properly ssh the both of the instances.

Point 6

nslookup on zazzercode.co gives me, 

$ nslookup -type=NS zazzercode.co
Server:     127.0.1.1
Address:    127.0.1.1#53

Non-authoritative answer:
zazzercode.co   nameserver = ns-1605.awsdns-08.co.uk.
zazzercode.co   nameserver = ns-1302.awsdns-34.org.
zazzercode.co   nameserver = ns-510.awsdns-63.com.
zazzercode.co   nameserver = ns-692.awsdns-22.net.

Authoritative answers can be found from:

nslookup on staging-storage.zazzercode.co gives me, 

$ nslookup -q=NS staging-storage.zazzercode.co
Server:     127.0.1.1
Address:    127.0.1.1#53

Non-authoritative answer:
staging-storage.zazzercode.co   canonical name = s-storage-us-west-2-483191837.us-west-2.elb.amazonaws.com.

Authoritative answers can be found from:
us-west-2.elb.amazonaws.com
    origin = ns-332.awsdns-41.com
    mail addr = awsdns-hostmaster.amazon.com
    serial = 1
    refresh = 7200
    retry = 900
    expire = 1209600
    minimum = 60

Point 7

Digging zazzercode.co gives me, 

$ dig TXT  ns-692.awsdns-22.net _amazonses.zazzercode.co

; <<>> DiG 9.9.2-P1 <<>> TXT ns-692.awsdns-22.net _amazonses.zazzercode.co
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 33984
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;ns-692.awsdns-22.net.      IN  TXT

;; Query time: 46 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Thu Jul 24 11:54:31 2014
;; MSG SIZE  rcvd: 49

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 30277
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;_amazonses.zazzercode.co.  IN  TXT

;; AUTHORITY SECTION:
zazzercode.co.      900 IN  SOA ns-692.awsdns-22.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400

;; Query time: 173 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Thu Jul 24 11:54:31 2014
;; MSG SIZE  rcvd: 137

I suspect it to be LoadBalancer issue. Is there a way to check if LoadBalancer is dropping the connection? Or What could be the issue here?

I'll put further details if needed.

(zazzercode.co is imaginary name here to hide the actual name till this point,actual is soothsayer.co everything else remaining the same)

References

Issues with EC2 Elastic Load Balancer DNS and routing

domain-name-system

0 Answers