`;const ta = root.querySelector('#dns-lines'); const btnRun = root.querySelector('#dns-run'); const btnStop = root.querySelector('#dns-stop'); const btnClear = root.querySelector('#dns-clear'); const typesWrap = root.querySelector('#dns-types'); const statusEl = root.querySelector('#dns-status'); const errorEl = root.querySelector('#dns-error'); const errorTextEl = root.querySelector('#dns-error-text'); const resultsEl = root.querySelector('#dns-results'); const delayInput = root.querySelector('#dns-delay'); const btnCopy = root.querySelector('#dns-copy-table'); const countEl = root.querySelector('#dns-count'); const progressEl = root.querySelector('#dns-progress'); const progressBarEl = root.querySelector('#dns-progress-bar'); const runTextEl = root.querySelector('#run-text');// Type pills với DPS branding const TYPE_LABELS = { 'ALL': 'TẤT CẢ', 'A': 'A', 'CNAME': 'CNAME', 'MX': 'MX', 'NS': 'NS', 'TXT': 'TXT' };let activeType = 'A'; RECORDS.forEach(t => { const b = document.createElement('button'); b.textContent = TYPE_LABELS[t] || t; b.className = 'dns-type-btn'; if (t === activeType) { b.classList.add('active'); } b.addEventListener('click',()=>{ if (isRunning) return; activeType = t; [...typesWrap.children].forEach(c => c.classList.remove('active')); b.classList.add('active'); }); typesWrap.appendChild(b); });// Domain count tracker với DPS colors function updateDomainCount() { const domains = ta.value.split(/\r?\n/) .map(s=>extractHostname(s)) .filter(Boolean); countEl.textContent = `${domains.length} tên miền`; if (domains.length > 100) { countEl.style.background = 'rgba(220,38,38,0.9) !important'; countEl.style.color = 'white !important'; } else if (domains.length > 50) { countEl.style.background = 'rgba(245,158,11,0.9) !important'; countEl.style.color = 'white !important'; } else if (domains.length > 0) { countEl.style.background = 'rgba(50,181,97,0.9) !important'; countEl.style.color = 'white !important'; } else { countEl.style.background = 'rgba(21,21,119,0.9) !important'; countEl.style.color = 'white !important'; } }ta.addEventListener('input', updateDomainCount); updateDomainCount();function clampDelay(){ let v = Number(delayInput.value || 0); if (!Number.isFinite(v) || v { if (e.key === '-') e.preventDefault(); });function extractHostname(input){ if(!input) return ''; try{ return new URL(input).hostname.replace(/\.$/,''); } catch(e){ return String(input).trim().replace(/^https?:\/\//i,'').replace(/^\/*/,'').split('/')[0].split('?')[0].replace(/\.$/,''); } }function sleep(ms){ return new Promise(r=>setTimeout(r, ms)); }function clearError(){ errorEl.style.display='none'; errorTextEl.textContent=''; } function showError(msg){ errorEl.style.display='flex'; errorTextEl.textContent=msg; } function setStatus(msg){ statusEl.textContent = msg; }function updateProgress(current, total) { if (total === 0) { progressEl.style.display = 'none'; return; } progressEl.style.display = 'block'; const percentage = Math.min((current / total) * 100, 100); progressBarEl.style.width = `${percentage}%`; }// Render table với DPS branding - Sử dụng div thay vì table elements function ensureTable(){ if(resultsEl.firstChild && resultsEl.firstChild.classList && resultsEl.firstChild.classList.contains('dns-table')) return resultsEl.firstChild; resultsEl.innerHTML = ''; const table = document.createElement('div'); table.className = 'dns-table'; const isMobile = window.innerWidth

`; resultsEl.appendChild(table); return table; }const allRows = []; function appendRows(rows){ const table = ensureTable(); const tbody = table.querySelector('.dns-table-body'); const frag = document.createDocumentFragment(); const isMobile = window.innerWidth { allRows.push(r); const tr = document.createElement('div'); tr.className = 'dns-table-row'; let dataColor = '#374151'; if (r.data === '(không có dữ liệu)') dataColor = '#9ca3af'; else if (r.data && r.data.startsWith('Lỗi:')) dataColor = '#dc2626'; tr.innerHTML = `

`; frag.appendChild(tr); }); tbody.appendChild(frag); btnCopy.disabled = false; btnCopy.classList.remove('success'); }async function queryDoH(domain, type){ const base = 'https://dns.google/resolve'; const params = new URLSearchParams(); params.set('name', domain); params.set('type', TYPE_CODE[type]); const url = `${base}?${params.toString()}`; const res = await fetch(url, { headers: { 'Accept':'application/json' }}); if(!res.ok) throw new Error(`HTTP ${res.status}`); return await res.json(); }let abortFlag = false; let isRunning = false;btnStop.addEventListener('click', ()=>{ abortFlag = true; setStatus('🛑 Đang dừng...'); });btnClear.addEventListener('click', () => { if (isRunning) return; resultsEl.innerHTML = `

`; allRows.length = 0; btnCopy.disabled = true; btnCopy.classList.remove('success'); clearError(); setStatus(''); progressEl.style.display = 'none'; });btnRun.addEventListener('click', async ()=>{ if (isRunning) return; clearError(); allRows.length = 0; abortFlag = false; isRunning = true;btnRun.disabled = true; runTextEl.textContent = '⏳ Đang chạy...'; btnStop.style.display = 'block'; btnClear.style.display = 'none'; [...typesWrap.children].forEach(b => { b.style.cursor = 'not-allowed'; b.style.opacity = '0.6'; });const delay = clampDelay();const domains = ta.value.split(/\r?\n/) .map(s=>extractHostname(s)) .filter(Boolean);if (!domains.length){ showError('Vui lòng nhập ít nhất 1 tên miền.'); resetUIState(); return; } if (domains.length > 100){ showError('Giới hạn 100 tên miền mỗi lần để tránh quá tải. Hãy chia nhỏ danh sách.'); resetUIState(); return; }const types = (activeType==='ALL') ? [...POPULAR] : [activeType]; const totalQueries = domains.length * types.length;resultsEl.innerHTML = ''; ensureTable();let completed = 0; for (let i=0; i 0){ const rows = json.Answer.map(a=>({ domain:d, type:t, name:a.name, ttl:a.TTL, data:a.data })); appendRows(rows); } else if (json && Array.isArray(json.Authority) && json.Authority.length > 0){ const rows = json.Authority.map(a=>({ domain:d, type:t, name:a.name, ttl:a.TTL, data:a.data })); appendRows(rows); } else { appendRows([{ domain:d, type:t, name:'', ttl:'', data:'(không có dữ liệu)' }]); } }catch(e){ appendRows([{ domain:d, type:t, name:'', ttl:'', data:`Lỗi: ${e.message}` }]); } completed++; updateProgress(completed, totalQueries); if (completed { b.style.cursor = 'pointer'; b.style.opacity = '1'; }); }function escapeCell(v){ if (v == null) return ''; const s = String(v); return s.replace(/\t/g, ' ').replace(/\r?\n/g, ' '); } function rowsToTSV(rows){ const header = ['Tên Miền','Loại','Tên','TTL','Dữ Liệu']; const lines = [header.join('\t')].concat(rows.map(r => [r.domain, r.type, r.name||'', r.ttl??'', r.data||''].map(escapeCell).join('\t'))); return lines.join('\n'); } async function copyText(text){ if (navigator.clipboard && navigator.clipboard.writeText){ await navigator.clipboard.writeText(text); } else { const ta = document.createElement('textarea'); ta.value = text; document.body.appendChild(ta); ta.select(); document.execCommand('copy'); document.body.removeChild(ta); } } btnCopy.addEventListener('click', async ()=>{ if (!allRows.length){ setStatus('❌ Không có dữ liệu để sao chép.'); return; } try{ await copyText(rowsToTSV(allRows)); setStatus('✅ Đã sao chép bảng vào clipboard!'); const originalText = btnCopy.textContent; btnCopy.textContent = '✅ Đã sao chép!'; btnCopy.classList.add('success'); setTimeout(() => { btnCopy.textContent = originalText; btnCopy.classList.remove('success'); }, 2000); }catch(e){ setStatus('❌ Sao chép thất bại: ' + e.message); } });// Window resize handler let resizeTimeout; window.addEventListener('resize', () => { clearTimeout(resizeTimeout); resizeTimeout = setTimeout(() => { if (resultsEl.firstChild && resultsEl.firstChild.classList && resultsEl.firstChild.classList.contains('dns-table')) { const currentRows = [...allRows]; allRows.length = 0; resultsEl.innerHTML = ''; if (currentRows.length > 0) { appendRows(currentRows); } } }, 100); });// Initialize copy button state btnCopy.disabled = true; })();Checking DNS records such as A, MX, CNAME helps ensure website and email operate stably and access speed is fast. This is a crucial factor for digital marketing success as user experience determines 75% of brand reliability. DPS.MEDIA has advised hundreds of SMEs and found that regularly checking DNS helps detect errors early and avoid business interruptions. Did you know it only takes a few minutes to quickly check these records?

Explore DNS Records and Their Crucial Role in Digital Marketing Strategy

What is a DNS record and why should marketers care?

DNS records such as A, MX, CNAME not only affect website stability but are also closely related to the effectiveness of digital campaigns:

– A record: trỏ tên miền về đúng IP máy chủ
– MX record: đảm bảo email gửi – nhận không bị thất lạc hoặc vô spam
– CNAME: hỗ trợ cấu hình phân phối nội dung qua subdomain, cloud hoặc tracking

An advertising campaign can fail just because of a wrong CNAME configuration causing pixel tracking to not work.

How does DNS impact Martech tools?

Email marketing platforms (e.g., Mailchimp, Sendgrid) require SPF, DKIM authentication via DNS records to:

– Tăng độ tin cậy email (Deliverability)
– Giảm tỷ lệ vào spam đến 62% (theo EmailToolTester 2022)
– Tuân thủ tiêu chuẩn DMARC nhằm bảo vệ domain khỏi giả mạo

If marketers do not understand DNS, they risk losing thousands of contacts due to emails being blocked or marked as spam.

DNS Checklist for Digital Marketers

• ✅ Check DNS A record – Website có tải ổn định?
• ✅ MX record hoạt động đúng – Email có bị trả lại không?
• ✅ Correctly installed SPF, DKIM, DMARC?
• ✅ Is CNAME redirect tracking working?
• ✅ SSL cert has no configuration errors from DNS?

Real-life Examples of DNS Errors Affecting Performance

Một SME ngành TMĐT từng triển khai chiến dịch retargeting thông qua custom domain CNAME tracking.Tuy nhiên, bản ghi bị lỗi do cấu hình sai phía DNS – kết quả góp phần khiến tỷ lệ click giảm 32% và CPA tăng gấp đôi.

Thách thức & lưu ý khi kiểm tra DNS

– Các hệ thống DNS có thời gian cập nhật (propagation) từ 1 đến 48 giờ – cần lên kế hoạch kiểm tra sớm.
– Không phải nền tảng DNS nào cũng thân thiện với non-tech marketer.
– Nên phối hợp với bộ phận IT hoặc DevOps để tránh sai sót kỹ thuật.

Brief takeaway: You don't need to code, but marketers need to understand DNS clearly to protect campaign performance and maintain user experience.

Detailed Guide to Checking A Records to Ensure Website Access Speed

What is an A record and why should it be checked?

Bản ghi A (Address Record) trong DNS ánh xạ tên miền sang địa chỉ IP cụ thể – là yếu tố quan trọng giúp trình duyệt truy cập đúng máy chủ lưu trữ web.Một bản ghi A không chính xác có thể khiến website bị chậm hoặc không truy cập được.

According to a report from CDN Planet (2023), over 35% of website slow loading incidents are due to DNS configuration errors, especially from A records not updated with the correct IP.

Detailed Steps to Check A Records

It's not difficult to check the A record yourself if you follow this checklist:

• Use the ping or nslookup command on Windows/macOS: nslookup yourdomain.com
• Access online tools such as DNSChecker.org or MXToolbox
• Compare the returned IP with the server IP provided by the hosting
• Kiểm tra TTL (Time to Live) của bản ghi – đề xuất < 300s for websites that require fast updates

If there is an IP mismatch or the record still points to the old server, update it immediately in the DNS manager (usually found in your domain or hosting account).

Standard A Record Parameter Checklist

Real-life Examples and Common Challenges

An e-commerce startup migrated from shared hosting to VPS but forgot to update the A record. Result: 48 hours of website downtime despite purchasing a high-speed package. This led to a 36% traffic loss during the sales event week (according to internal Google Analytics, 2023).

Brief takeaway

Bản ghi A chính xác là nền tảng của hiệu suất website. Hãy kiểm tra ngay sau khi thay đổi IP, chuyển host hoặc thấy dấu hiệu chậm tải – vì tốc độ truy cập nhanh bắt đầu từ chính cấu hình DNS bạn đang dùng.

Steps to Check MX Records to Ensure Smooth Business Email Operation

1. Identify the current email provider

First, you need to know which email service your business is using (Google Workspace, Microsoft 365, etc.). Each provider will have different requirements for records. MX (Mail Exchange).- Ví dụ: Google Workspace yêu cầu bản ghi MX trỏ đến mail servers như: ASPMX.L.GOOGLE.COM, ALT1, ALT2…
– Nếu chưa chắc chắn,thử gửi email ra ngoài và xem được không,hoặc tra lại hợp đồng với IT/đối tác cũ.

Note: Using the wrong record can cause all emails to be undeliverable.

2. Check current MX records using online tools

There are many free tools that help you retrieve MX records in just a few seconds:

• mxtoolbox: https://mxtoolbox.com
• Google Admin Toolbox: https://toolbox.googleapps.com/apps/dig/

Ví dụ, khi kiểm tra miền abccompany.vn trên MXToolbox và thấy mail server trả về “mx.yandex.net”,thì có nghĩa hệ thống email đang chạy qua Yandex.

3. Standard MX Configuration Checklist

Below is a list of items to carefully check when configuring MX:

• ✔️ Correct mail server name (matching the provider's domain)
• ✔️ At least one backup system (multiple MX records with different priority values)
• ✔️ No duplicate or conflicting records
• ✔️ TTL should not be lower than 300 seconds unless testing is required

4. Common MX Record Checklist

5. Real Business Example: Lost Email Due to MX Error

In 2022, an e-commerce business in Ho Chi Minh City reported losing all customer contact for nearly 3 days. The cause was the MX record being deleted when switching DNS providers without backing up the old configuration. According to the internal IT report, revenue was affected by up to 12%, equivalent to more than 500 million VND (Source: Internal technical report, 2022).

Takeaway:

Always check and maintain accurate MX records to avoid email service interruptions. Periodic checks every 3-6 months are a simple but effective way for any business to maintain professional communication.

Quick Tips for Checking CNAME Records and Their Application in Online Brand Management

How to Quickly Check CNAME Records

To check the record CNAME,you can use online DNS checking tools such as:

– Google Admin Toolbox (toolbox.googleapps.com)
– DNSChecker.org hoặc mxtoolbox.com
– Command line: nslookup -type=CNAME subdomain.domain.com

An online tool provides almost instant results, very suitable for those with little technical knowledge. Ensure that the CNAME record does not duplicate or conflict with other records (such as an A record).

Applications of CNAME in Brand Management

CNAME record is used to map subdomains like blog, shop, or mail to a third-party subdomain, for example:

– blog.tenmien.com → hosted-by.medium.com
– shop.tenmien.com → stores.shopify.com

This helps maintain brand consistency across external platforms. According to data from HubSpot Report 2022, 68% of small and medium businesses use subdomains for content or ecommerce to maintain consistent brand identity.

Checklist for implementing CNAME for brands

• ✅ Identify the subdomain to be mapped (e.g., blog, support, shop)
• ✅ Check the current CNAME record using a DNS checker tool
• ✅ Xác nhận giá trị CNAME từ bên cung cấp nền tảng (Medium, Zendesk,…)
• ✅ Test the operation of each link after updating
• ✅ Monitor TTL (time to Live) to know the record update time

Real-life example: Checking CNAME for event landing page

An event organizing brand uses a subdomain event.domain.com to point to an external platform like Eventbrite. After creating the CNAME record, they check using nslookup and verify that it points correctly to pages.eventbrite.com. This helps maintain brand quality without being split across long or hard-to-read URLs.

Be cautious of risks when using CNAME

– Nếu ghi đè nhầm bản ghi root domain → gây mất truy cập hoàn toàn.
– Một vài CDN hoặc dịch vụ email không cho phép sử dụng CNAME ở cấp cao.- Dễ bỏ sót cập nhật DNS khi bên thứ ba thay đổi endpoint.

Brief Takeaway

CNAME is an optimal tool to expand your brand without sacrificing consistency. Always check records regularly, especially before major campaigns, to avoid hidden errors that can reduce your brand's credibility in the digital environment.

Effective Tools for Checking and Managing DNS Records Specifically for SMEs

Reliable and free DNS tools

For small and medium enterprises (SMEs), choosing an effective DNS tool can help avoid website and email disruptions. Below are some popular, easy-to-use tools highly rated by the technical community:

• MXToolbox: Check A, MX, SPF, DKIM in just a few seconds
• Google Admin Toolbox: Intuitive interface, suitable for beginners
• DNSChecker: Supports DNS resolution checks by country
• WhatsMyDNS.net: Check DNS record updates in real time globally

Periodic DNS record checklist for SMEs

Regularly checking important DNS records helps maintain the stability of email and website systems. SMEs can implement a bi-weekly check schedule with the following steps:

• ✔️ Check that the A record points to the correct current IP
• ✔️ Cross-check CNAME records with linked services (subdomain, CDN)
• ✔️ Review MX, SPF, DKIM records to ensure email works properly
• ✔️ Compare TTL to determine effective update times

Summary table of DNS tools by purpose

Real-life example from a retail business

An SME in the retail sector once experienced missed orders due to incorrect MX records after switching to a new email provider. After checking with MXToolbox and updating the correct records, the inbox delivery rate increased back to 95% in just 24 hours (according to internal Q2/2023 statistics).

Risks if DNS is not checked regularly

If DNS records are not checked regularly, businesses may encounter the following errors:

• ❌ Website inaccessible due to incorrect A record
• ❌ Email sent to spam or completely blocked
• ❌ Subdomain loses connection with third-party services

Brief takeaway

For SMEs, using free tools and regularly checking DNS is a simple but extremely effective way to protect daily digital operations. Choose the right tool for your needs to save time and reduce operational risks.

Advice from DPS MEDIA to Optimize DNS Records Supporting Digital Marketing Campaigns

Understand the correct role of DNS records

DNS records are a foundational factor that directly affects website visibility and email deliverability in digital marketing campaigns. Some important records to pay attention to:

– A record: Points the domain to the main server IP address
– MX record: Supports sending/receiving emails, especially important for Email Marketing
– CNAME: Easily configures subdomains for landing pages, remarketing, etc.

A 2023 study by HubSpot showed that: 71% of failed email campaigns are due to DNS setup errors (source: HubSpot Email Deliverability Report 2023).

Effective DNS configuration checklist for marketers

To optimize DNS for marketing activities, make sure to follow these steps:

• Verify the domain with platforms like Google, Meta, Zoho using TXT records
• Set up SPF, DKIM, and DMARC to increase email reliability
• Use CNAME records to configure custom domains for landing pages
• Check TTL time to ensure quick updates when running A/B tests

Sample DNS records to set up for email marketing

Practical example from a (anonymous) client

Một doanh nghiệp SME trong ngành dịch vụ đã cải thiện tỷ lệ mở email từ 8% lên 24% sau khi chỉnh lại bản ghi SPF và DKIM đúng chuẩn theo đề xuất từ DPS.MEDIA. Thời gian thiết lập chỉ mất 3 giờ, nhưng kết quả duy trì ổn định trong suốt 6 tháng sau chiến dịch.

Warning: Common risks

– Cấu hình sai MX có thể khiến email không gửi/nhận được
– TTL quá cao làm chậm khả năng cập nhật nội dung test A/B
– Thiếu bản ghi TXT xác thực có thể khiến chiến dịch quảng cáo bị từ chối (ví dụ: Meta Business Suite)

Quick summary:

Tối ưu DNS không chỉ là nhiệm vụ kỹ thuật – mà là một phần quan trọng giúp chiến dịch marketing số đạt hiệu quả cao, từ hiển thị landing page, bảo mật email đến tăng tốc chiến dịch remarketing. Triển khai đúng cách, marketer sẽ có “đòn bẩy ngầm” giúp tăng ấn tượng và tỷ lệ chuyển đổi.

Proactively Handling DNS Record Issues Helps Businesses Increase Stability and Reliability

Reasons why businesses need to monitor DNS regularly

Incorrect or missing DNS records can result in emails not being sent, websites being inaccessible, or internal services being disrupted. According to the Digital Infrastructure Security Report by IDC (2022), over 36% of small businesses have experienced downtime due to undetected DNS errors. Some common consequences of poor DNS control:

– Website bị gián đoạn truy cập trên toàn quốc
– Tổn thất lượt truy cập, doanh thu thương mại điện tử
– Email doanh nghiệp bị đánh dấu spam hoặc không gửi được
– Lộ thông tin nếu DNS bị giả mạo (DNS Spoofing)

Proactive checklist for handling and preventing DNS issues

Instead of only reacting when errors are detected, businesses should implement a regular DNS record check plan to detect and resolve issues early:

• ✔ Regularly check A, MX, and CNAME records weekly
• ✔ Set up alerts if the domain expires or DNS parameters change
• ✔ Monitor DNS uptime with tools like UptimeRobot, Pingdom
• ✔ Log all DNS changes for easier auditing
• ✔ Training the technical team to handle domain name resolution errors

Sample DNS record monitoring table plays an important role

Real-life example: 8 hours downtime due to MX record error

Một doanh nghiệp thương mại điện tử vừa ra mắt chiến dịch email marketing nhưng không nhận được phản hồi từ người dùng. Sau 8 giờ truy vấn mới phát hiện bản ghi MX trỏ sai SMTP server. Kết quả là mất hơn 1.200 đơn hàng tiềm năng – theo tổng hợp nội bộ (2023).

Note on implementing DNS to prevent domain name resolution errors

– Tránh sử dụng DNS miễn phí nếu doanh nghiệp có lượng traffic cao
– Sử dụng DNS redundancy (như Cloudflare + DNS gốc)
– Kết hợp kiểm tra DNS với việc đánh giá bảo mật SSL/TLS định kỳ

Takeaway:

Proactively controlling DNS records not only helps businesses maintain stable operations but also reduces the risk of data loss, lost orders, and long-term reputation damage. A simple, regularly updated plan can make a big difference.

Valuable lessons

Checking DNS records such as A, MX, and CNAME helps ensure website stability. It also supports quick troubleshooting of connection issues.

Try out the DNS lookup tools you just read about. Start by checking your business domain.

You can learn more about optimizing website speed or configuring SEO-standard SSL. This is an important next step in your digital strategy.

DPS.MEDIA always accompanies Vietnamese SMEs on their digital transformation journey. Join the discussion and share your questions in the comments below!