Unable to process system update with apt-get update

Question

I'm getting the following error whenever I try to install a package or update.

ubuntu@ip-172-31-60-64:~$ sudo apt-get update
Err:1 http://archive.ubuntu.com/ubuntu xenial InRelease
Temporary failure resolving 'archive.ubuntu.com'
Err:2 http://security.ubuntu.com/ubuntu xenial-security InRelease
Temporary failure resolving 'security.ubuntu.com'
Err:3 http://archive.ubuntu.com/ubuntu xenial-updates InRelease
Temporary failure resolving 'archive.ubuntu.com'
Err:4 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
Temporary failure resolving 'archive.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-updates/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-backports /InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/xenial-security/InRelease  Temporary failure resolving 'security.ubuntu.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.

I've seen other answers relating to this problem. But, none of them worked. The instance is running in AWS and the traffic rules are properly set.

Ifconfig output as follows..

ifconfig
eth0      Link encap:Ethernet  HWaddr 12:d2:b3:9a:b4:c8
      inet addr:172.31.60.64  Bcast:172.31.63.255  Mask:255.255.240.0
      inet6 addr: fe80::10d2:b3ff:fe9a:b4c8/64 Scope:Link
      UP BROADCAST RUNNING PROMISC MULTICAST  MTU:9001  Metric:1
      RX packets:3436 errors:0 dropped:0 overruns:0 frame:0
      TX packets:3359 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:277901 (277.9 KB)  TX bytes:307892 (307.8 KB)

lo        Link encap:Local Loopback
      inet addr:127.0.0.1  Mask:255.0.0.0
      inet6 addr: ::1/128 Scope:Host
      UP LOOPBACK RUNNING  MTU:65536  Metric:1
      RX packets:8 errors:0 dropped:0 overruns:0 frame:0
      TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1
      RX bytes:480 (480.0 B)  TX bytes:480 (480.0 B)

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
      inet addr:10.8.0.1  P-t-P:10.8.0.2  Mask:255.255.255.255
      UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:100
      RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

The nslookup is...

nslookup archive.ubuntu.com
;; connection timed out; no servers could be reached

This question has been marked as duplicate. But, the original question did not resolve my issue.

Contents of /etc/hosts

   127.0.0.1 localhost
   127.0.1.1 ip-172-31-60-64

   # The following lines are desirable for IPv6 capable hosts
   ::1 ip6-localhost ip6-loopback
   fe00::0 ip6-localnet
   ff00::0 ip6-mcastprefix
   ff02::1 ip6-allnodes
   ff02::2 ip6-allrouters
   ff02::3 ip6-allhosts