Visa Interview Questions (12+ Questions)

Learn how to diagnose and restore outbound SMTP connectivity using Linux Bash commands and firewall management. This guide covers identifying active firewalls, inspecting outbound rules, allowing SMTP port 25, testing connectivity, and verifying fixes, essential for troubleshooting email delivery issues and managing host-level firewall policies in production systems.

Kubernetes NGINX Ingress Canary: 10% app-v2 Auto-Rollback hashicorp/http-echo. Production-grade canary deployment in canary namespace with NGINX Ingress traffic splitting: 90% app-v1 (3 replicas) vs 10% app-v2 (1 replica) using hashicorp/http-echo containers. Dual Ingress app-ingress + app-ingress-canary with canary-weight: 10, header routing X-Canary: true, and auto-rollback script on >5 v2 pod restarts. Perfect for progressive delivery, A/B testing infrastructure, golden path releases, SRE automation, and zero-risk production deployments.

Implement immutable artifact promotion patterns in GitHub Actions. Learn to build Docker images once, pass their unique digests between jobs using outputs and needs, and deploy to production without rebuilding.

Learn to use GitHub Actions Service Containers. Spin up ephemeral databases (like PostgreSQL) inside your workflow for robust integration testing using the services keyword.

def subsets(nums: list[int]) -> list[list[int]]:
res = []

def dfs(i, current_subset):
    res.append(current_subset.copy())
    
    for j in range(i, len(nums)):
        current_subset.append(nums[j])
        dfs(j + 1, current_subset)
        current_subset.pop()
        
dfs(0, [])
return res

Read customer records from a CSV file, check for existing records in a SQLite database table based on ID field, and insert only new records to avoid duplicates.

WITH combined AS (
SELECT
i.investment_id,
COALESCE(fd.fund_id, i.fund_id) AS fund_id,
COALESCE(f.firm_id, fd.firm_id) AS firm_id,
f.firm_name,
f.founded_year,
f.location,
fd.fund_name,
fd.fund_size,
fd.fund_start_year,
fd.fund_end_year,
i.company_name,
i.investment_amount,
i.investment_date
FROM {{ ref("firms") }} f
FULL OUTER JOIN {{ ref("funds") }} fd
ON f.firm_id = fd.firm_id
FULL OUTER JOIN {{ ref("investments") }} i
ON fd.fund_id = i.fund_id
)
SELECT *
FROM combined
WHERE NOT (
investment_id IS NULL
AND fund_id IS NULL
AND firm_id IS NULL
AND firm_name IS NULL
AND founded_year IS NULL
AND location IS NULL
AND fund_name IS NULL
AND fund_size IS NULL
AND fund_start_year IS NULL
AND fund_end_year IS NULL
AND company_name IS NULL
AND investment_amount IS NULL
AND investment_date IS NULL
)

Master data aggregation in PySpark. Learn how to join tables, perform multi-column GroupBy operations, and cast aggregated sums to specific data types.

Interview Question: SQL Query for Employee Performance and Bonus Status

Objective:

Crafting an SQL query to showcase employees' names, performance scores, annual salaries, and bonus statuses is an essential exercise in database management. This query will help in evaluating and rewarding ...

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def trap(height: list[int]) -> int:
if not height:
return 0

l, r = 0, len(height) - 1
left_max, right_max = height[l], height[r]
res = 0

while l < r:
    if left_max < right_max:
        l += 1
        left_max = max(left_max, height[l])
        res += left_max - height[l]
    else:
        r -= 1
        right_max = max(right_max, height[r])
        res += right_max - height[r]
        
return res

def find_itinerary(tickets: list[list[str]]) -> list[str]:
adj = defaultdict(list)

tickets.sort(reverse=True)

for src, dst in tickets:
    adj[src].append(dst)
    
res = []

def dfs(src):
    while adj[src]:
        dst = adj[src].pop()
        dfs(dst)
    res.append(src)
    
dfs("JFK")
res.reverse()

return res

How to Identify Customers with Multiple Orders on the Same Date in SQL

Interview Question Objective

Write an SQL query to identify customers who have placed multiple orders on the same date. The query should return distinct pairs of customer names and order dates, sorted by the order date...

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