
Ask HN: Are AWS Multi AZ ELB IPs Virtual? - jjoe
Setup:<p>Multi AZ ELB hostname: myapp.elb.amazonaws.com
Hostname resolves to IPs (Round Robin): 1.2.3.4 and 5.6.7.8<p>In the event that the LB service behind IP 1.2.3.4 fails, does AWS remove the IP 1.2.3.4 from the hostname RR rotation or does it simply keep the same IP (i.e. virtual) but points to a healthier LB service?<p>Documentation doesn&#x27;t seem to discuss this detail. Hopefully someone here knows :)
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mattkrea
Wait.. are you using the IP of the ELB instead of the A or AAA record and then
using Route 53's round robin DNS? You should absolutely not be doing that if
so but if you _must_ you should enable health check on Route 53.

Edit: Here is the mention from the ELB panel.

> Because the set of IP addresses associated with a LoadBalancer can change
> over time, you should never create an "A" record with any specific IP
> address.

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jjoe
No I'm not using ELB IPs directly. My concern is this scenario:

1) ELB with IP 1.2.3.4 develops an issue (AWS internal outage)

2) DNS resolver for an end user of my app has the pair
myapp.elb.amazonaws.com/1.2.3.4 cached previously for longer than the TTL
(resolvers are notorious for this)

3) When end user resumes work within the app, they're referencing the LB at
1.2.3.4, which is down.

Hence my question. Is the mapping of 1.2.3.4 to its respective LB static or
virtual? Meaning, does AWS keep moving the 1.2.3.4 around to a healthy LB
service seamlessly?

Thanks

