{"v":1,"videos":[{"slug":"do-you-make-this-union-vs-union-all-mistake","title":"Do you make this UNION vs UNION ALL mistake?","description":"Learn how UNION removes duplicate rows while UNION ALL retains all rows and runs cheaper by skipping de-duplication.","subject":"dbms","subjectName":"DBMS and SQL","practice":"dbms","daily":null,"tags":["sql","dbms","union","union all","database"],"publishedAt":"2026-10-29T02:34:16.231Z","langs":{"hi":{"name":"Hinglish","title":"Do you make this UNION vs UNION ALL mistake?","hook":"Will duplicates be kept or dropped?","duration":69.3,"v720":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/do-you-make-this-union-vs-union-all-mistake/hi-078a528e-720.mp4","v1080":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/do-you-make-this-union-vs-union-all-mistake/hi-a30acda9-1080.mp4","poster":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/do-you-make-this-union-vs-union-all-mistake/hi-f1a796c6-poster.webp","quiz":{"askEnd":47.95,"revealStart":50.4,"q":"Table x holds 1, 2, 2 and table y holds 2, 3. How many rows does this return?","options":["5","3","4","2"],"answer":0},"scenes":[{"id":"hook","start":0},{"id":"code","start":6.01},{"id":"compare","start":14.25},{"id":"rules","start":24.62},{"id":"makeover","start":32.69},{"id":"quiz","start":40.95},{"id":"outro","start":59.42}],"captions":[{"start":0.4,"end":5.81,"text":"Galat SQL logic tumhe interview mein reject karwayega, three rows bolna totally wrong hai."},{"start":6.26,"end":14.05,"text":"Query dekho: table x deta hai three rows aur table y deta hai two rows, isliye UNION ALL keeps all, yaani total five rows."},{"start":14.5,"end":24.42,"text":"Ab sabse important part, plain UNION duplicate rows removes karta hai, leaving three rows, lekin UNION ALL keeps all five rows bina filtering."},{"start":24.87,"end":32.49,"text":"Kabhi assume mat karna ki duplicates drop honge, comma lagane se cross join banega, hamesha columns count aur data types match karo."},{"start":32.94,"end":40.75,"text":"Interview mein confident hokar bolo ki UNION ALL five rows dega, kyonki yeh duplicates retain karta hai aur de-duplication skip karke cheaper banta hai."},{"start":41.2,"end":47.95,"text":"Screen par question dekho, video pause karo aur choose karo: kya answer A, B, C ya D hoga, turant screen par tap karo."},{"start":50.4,"end":59.22,"text":"Correct answer A hai, UNION ALL pancho rows rakhta hai, jabki plain UNION duplicates hatakar sirf three rows return karta hai."},{"start":59.67,"end":67.5,"text":"Placement interview revision ke liye yeh table save kar lo, aur aise tricky DBMS questions InternDoor par daily practice karte raho."}]}}},{"slug":"what-does-a-tls-certificate-actually-prove","title":"What does a TLS certificate actually prove?","description":"Learn what a TLS certificate verifies during the handshake and how asymmetric and symmetric encryption secure connection data.","subject":"cn","subjectName":"Computer networks","practice":"cn","daily":null,"tags":["computer networks","tls certificate","tls handshake","asymmetric encryption"],"publishedAt":"2026-10-28T20:03:58.249Z","langs":{"en":{"name":"English","title":"What does a TLS certificate actually prove?","hook":"What does a TLS certificate actually prove?","duration":69.47,"v720":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/what-does-a-tls-certificate-actually-prove/en-2107a5e0-720.mp4","v1080":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/what-does-a-tls-certificate-actually-prove/en-a6ab6f38-1080.mp4","poster":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/what-does-a-tls-certificate-actually-prove/en-40978e70-poster.webp","quiz":{"askEnd":48.79,"revealStart":51.24,"q":"During a TLS handshake, what does the server's certificate prove to the browser?","options":["That the server really owns the domain, vouched for by a certificate authority the browser trusts","That the website is free of malware","That the connection is faster than plain HTTP","That the browser is the one the server expected"],"answer":0},"scenes":[{"id":"hook","start":0},{"id":"handshake-seq","start":6.03},{"id":"cert-proof","start":14.36},{"id":"crypto-roles","start":22.56},{"id":"trap-check","start":32.48},{"id":"quiz","start":41.69},{"id":"outro","start":59.64}],"captions":[{"start":0.4,"end":5.83,"text":"Freshers get rejected here: claiming a TLS certificate proves a website lacks malware."},{"start":6.28,"end":14.16,"text":"During the handshake, the server sends its certificate, proves it owns the matching private key, and both sides agree on a shared session key."},{"start":14.61,"end":22.36,"text":"Now the part most people miss: the certificate binds the domain name to a public key, signed by a trusted authority, needing private key proof."},{"start":22.81,"end":32.28,"text":"Asymmetric operations are slow, so TLS uses them during handshake to agree on keys, but switches to fast symmetric encryption for bulk page data."},{"start":32.73,"end":41.49,"text":"Never claim certificates check malware or browser identity; they strictly prove that the server really owns the domain, vouched by an authority you trust."},{"start":41.94,"end":48.79,"text":"Look at the placement question on your screen right now, pause the video, and tap your chosen answer before the timer runs out."},{"start":51.24,"end":59.44,"text":"Option A is correct because the certificate validates domain ownership through a trusted authority, while B is wrong since certificates ignore malware completely."},{"start":59.89,"end":67.68,"text":"Save this comparison summary table before your next technical interview, and practice core computer networks questions for free on InternDoor today."}]},"hi":{"name":"Hinglish","title":"What does a TLS certificate actually prove?","hook":"What does a TLS certificate really prove?","duration":68.3,"v720":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/what-does-a-tls-certificate-actually-prove/hi-d1fd6ce7-720.mp4","v1080":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/what-does-a-tls-certificate-actually-prove/hi-824e343f-1080.mp4","poster":"https://vp3w41iulpl4wc7s.public.blob.vercel-storage.com/videos/what-does-a-tls-certificate-actually-prove/hi-87701fb3-poster.webp","quiz":{"askEnd":48.13,"revealStart":50.58,"q":"During a TLS handshake, what does the server's certificate prove to the browser?","options":["That the server really owns the domain, vouched for by a certificate authority the browser trusts","That the website is free of malware","That the connection is faster than plain HTTP","That the browser is the one the server expected"],"answer":0},"scenes":[{"id":"hook","start":0},{"id":"handshake-seq","start":6.11},{"id":"cert-proof","start":14.07},{"id":"crypto-roles","start":22.94},{"id":"trap-check","start":31.79},{"id":"quiz","start":41.01},{"id":"outro","start":57.97}],"captions":[{"start":0.4,"end":5.91,"text":"Yeh galat answer tumhara interview kharab karega, TLS certificate malware nahi rokte."},{"start":6.36,"end":13.87,"text":"TLS handshake mein server apna certificate send karta hai, private key ka possession prove karta hai, aur dono ek shared session key par agree karte hain."},{"start":14.32,"end":22.74,"text":"Ab sabse important part, certificate domain ko public key se bind karta hai, trusted authority ise sign karti hai aur server matching private key dikhata hai."},{"start":23.19,"end":31.59,"text":"Asymmetric crypto slow hoti hai, isliye TLS handshake mein keys agree karne tak rukta hai, phir fast symmetric cipher bulk data encrypt karta hai."},{"start":32.04,"end":40.81,"text":"Certificate kabhi malware scan nahi karta aur na hi browser identity dekhata hai; yeh sirf domain ownership prove karta hai, vouched by trusted authority."},{"start":41.26,"end":48.13,"text":"Screen par networking ka question dekho, video pause karo aur socho ki TLS handshake mein browser ko certificate kya prove karta hai."},{"start":50.58,"end":57.77,"text":"Correct answer A hai; certificate trusted authority ke zariye domain ownership prove karta hai, option B galat hai kyunki yeh malware nahi rokta."},{"start":58.22,"end":66.51,"text":"Handshake authentication aur encryption ka yeh table interview se pehle save kar lo, aur computer networks ke core concepts InternDoor par practice karo."}]}}}]}