← SOA-C02·Amazon Web Services

Question 787 of 1,546

Networking and Content Delivery →hardMultiple ChoiceObjective-mapped

Why Route53 Alias Record Updates Take Time: TTL Caching Explained

This SOA-C02 practice question tests your understanding of networking and content delivery. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A company uses Amazon Route 53 as its DNS service. They have a domain example.com with an alias record pointing to an Application Load Balancer (ALB). Recently, they updated the ALB's DNS name, but the Route 53 record was not updated. Users are still being directed to the old ALB, which has been decommissioned. The SysOps administrator updates the alias record to point to the new ALB DNS name. However, users still experience errors for several hours. What is the most likely reason?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

A
Route 53 requires time to propagate changes globally
Why wrong: Alias records are updated instantly in Route 53.
B
The alias record was not saved correctly
Why wrong: If saved, it should work; the issue is caching.
C
The TTL on the DNS record is set too high, causing client-side caching
A high TTL means clients cache the old IP until the TTL expires.
D
The domain is using DNSSEC, which delays updates
Why wrong: DNSSEC does not affect caching.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The TTL on the DNS record is set too high, causing client-side caching

Option C is correct because alias records in Route 53 are not subject to TTL-based caching for the alias target resolution itself, but the DNS query response from the resolver to the client still includes a TTL value. When the TTL is set too high, clients and intermediate resolvers cache the old DNS response (pointing to the decommissioned ALB) for the duration of that TTL, causing continued errors even after the Route 53 record is updated. The alias record update propagates instantly within Route 53's authoritative infrastructure, but cached records at clients and recursive resolvers must expire before users reach the new ALB.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Route 53 requires time to propagate changes globally
Why it's wrong here
Alias records are updated instantly in Route 53.
✗
The alias record was not saved correctly
Why it's wrong here
If saved, it should work; the issue is caching.
✓
The TTL on the DNS record is set too high, causing client-side caching
Why this is correct
A high TTL means clients cache the old IP until the TTL expires.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The domain is using DNSSEC, which delays updates
Why it's wrong here
DNSSEC does not affect caching.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume alias records update instantly for all users, forgetting that the TTL in the DNS response controls client-side and resolver caching, which can cause delays even after the authoritative record is changed.

Detailed technical explanation

How to think about this question

Alias records in Route 53 are special because they link to AWS resources (like ALBs) and are resolved at the Route 53 edge without a separate DNS query chain, but the response to the client still includes a TTL (default 60 seconds for alias records to ALBs). If the TTL was manually set to a high value (e.g., 86400 seconds), clients and recursive resolvers will cache the old IP address for up to 24 hours, causing persistent failures. This is a common misconfiguration where administrators assume alias records bypass caching entirely, but the TTL field in the response still governs client-side cache duration.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.

Visual reference

Quick reference

Common DNS Record Types

Record	Purpose	Example
A	IPv4 address mapping	example.com → 93.184.216.34
AAAA	IPv6 address mapping	example.com → 2606:2800::1
CNAME	Alias to another hostname	www → example.com
MX	Mail server for domain	example.com → mail.example.com (priority 10)
TXT	Text data (SPF, DKIM, verification)	v=spf1 include:_spf.example.com ~all
NS	Authoritative name servers	example.com NS ns1.example.com
PTR	Reverse DNS (IP → hostname)	34.216.184.93.in-addr.arpa → example.com
SOA	Zone authority record	Primary NS, admin email, serial, TTL defaults

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Related SOA-C02 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

Monitoring, Logging, and Remediation practice questions

Practise SOA-C02 questions linked to Monitoring, Logging, and Remediation.

Reliability and Business Continuity practice questions

Practise SOA-C02 questions linked to Reliability and Business Continuity.

Deployment, Provisioning, and Automation practice questions

Practise SOA-C02 questions linked to Deployment, Provisioning, and Automation.

Security and Compliance practice questions

Practise SOA-C02 questions linked to Security and Compliance.

Networking and Content Delivery practice questions

Practise SOA-C02 questions linked to Networking and Content Delivery.

Cost and Performance Optimization practice questions

Practise SOA-C02 questions linked to Cost and Performance Optimization.

SOA-C02 fundamentals practice questions

Practise SOA-C02 questions linked to SOA-C02 fundamentals.

SOA-C02 scenario practice questions

Practise SOA-C02 questions linked to SOA-C02 scenario.

SOA-C02 troubleshooting practice questions

Practise SOA-C02 questions linked to SOA-C02 troubleshooting.

Practice this exam

Start a free SOA-C02 practice session

Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.

10 questions 20 questions 30 questions 50 questions Timed 30

SOA-C02 practice-test guide →Study guide →Browse all practice tests

FAQ

Questions learners often ask

What does this SOA-C02 question test?

Networking and Content Delivery — This question tests Networking and Content Delivery — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The TTL on the DNS record is set too high, causing client-side caching — Option C is correct because alias records in Route 53 are not subject to TTL-based caching for the alias target resolution itself, but the DNS query response from the resolver to the client still includes a TTL value. When the TTL is set too high, clients and intermediate resolvers cache the old DNS response (pointing to the decommissioned ALB) for the duration of that TTL, causing continued errors even after the Route 53 record is updated. The alias record update propagates instantly within Route 53's authoritative infrastructure, but cached records at clients and recursive resolvers must expire before users reach the new ALB.

What should I do if I get this SOA-C02 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

About these practice questions

Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →

How Courseiva writes practice questions · Editorial policy

Keep practising

Question Discussion

Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.

Loading comments…

This SOA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SOA-C02 exam.