How do I print them double-sided?

Double-sided, flip on the long edge. Every front sheet is followed by its own already-mirrored back sheet, so print them in the order they come and every answer lands on its own card.

Can I edit the cards?

Yes, and that is half the point. Once you own the deck, the "Buy & edit" button here opens all 36 cards in the free flash card maker on this site — reword a definition, delete the ones you do not teach, add your own, and print at anything from two to nine cards a page, rather than the fixed eight of the PDF.

Can I print a set for every student?

Yes. Personal and classroom licence: unlimited printing, every class you teach, every year you teach it. It does not cover reselling the file or passing it on to a colleague.

What if I find a card that is wrong?

Tell us and we fix it, and we publish what changed. We have withdrawn a whole deck from sale for being out of date rather than quietly patch it.

Do I need an account?

No. $2.99 at Stripe, the file downloads on the way back, and the deck stays unlocked in this browser.

Printable flash cards

36 Common TCP & UDP Ports flashcards, ready to print. $2.99, once.

One payment buys the deck twice over: the printable PDF and every card unlocked to play online. Eight to a sheet, cut guides on every card, and the answer sheet already mirrored so a long-edge duplex print puts every answer on the back of its own question. 15 pages, US Letter, black and white. Grades 9–12.

Both halves, one price. A single deck printable is $1.29 on the store shelf and unlocking a deck to play is $2.99 — $4.28 for the two. Here they are the same $2.99 purchase, so you save $1.29 — and there is one receipt to keep instead of two.

Includes every card unlocked to play online — $4.28 bought separately. One payment, no account, no renewal.

Same price, opens in the editor. Reword any card, add your own, print it your way.

Not sure yet? The first 30 cards of this deck are free to play and free to print, right now, with no email. Play the free 30 · Print the free 30

15 pages, and the backs are already right

Every front sheet is followed by its own back sheet with the rows reversed. Print double-sided, flip on the long edge, and answer number 7 is behind question number 7. Print a deck you built yourself, flip on the short edge, and every answer lands on the wrong card — which nobody finds out until sixty cards have been cut apart.

36 cards — counted out of the file, not rounded up
Eight cards a sheet, with cut guides
US Letter PDF, black and white, photocopier-friendly
Print a set per student, every class, every year

36 cards. These are the ports the Network+ and CCNA objectives actually ask for; the IANA registry holds thousands more, and listing them would be padding, not studying.

Every card here is cited to two independent sources

Two different organisations — not a standards body and a website reprinting it — and a script refuses the card if the two disagree, so the check runs on every card rather than on the ones somebody remembered to look at. A second specialist then re-verified this deck from sources of their own, without reading our citations first. A further 5,420 cards across 30 other decks were read end to end by a subject specialist instead, and we say which is which on every deck rather than averaging the two into one flattering word.

What 36 printed cards do that a screen does not

A phone deck is one card at a time. A printed deck is a pile you can split: the ones you know, the ones you nearly know, and the ones you keep missing. That third pile is the entire study session, and it is the thing a scrolling app hides from you.

Print once, use all year. The licence covers a set per student, every class, every year.
No device, no login, no data. Works in a cover lesson, on a bus, or at a kitchen table. Grades 9–12, filed under career, tech & modern.
Change what you disagree with. Every card loads into the free maker on this site. Reword it, drop it, add your own, reprint.

Here are the first 30 cards, written out

Check them against your own textbook before you spend anything. If you do not like how they are worded, do not buy the deck — that is what this list is for.

Port 20: FTP data connection — TCP; the default data port is one below the control port
Port 21: FTP control connection — TCP; commands and replies only, data uses a separate connection
Port 22: SSH, Secure Shell — TCP
Port 23: Telnet — TCP; remote terminal, sent in the clear
Port 25: SMTP — TCP; server-to-server mail transfer
Port 53: DNS — UDP for most queries, TCP for zone transfers and large replies; RFC 7766 requires TCP support too
Port 67: DHCP / BOOTP server — UDP; the port clients send requests to
Port 68: DHCP / BOOTP client — UDP; the port servers reply to
Port 69: TFTP — UDP; no login, no encryption
Port 80: HTTP — TCP; the default port of the http:// scheme
Port 110: POP3 — TCP; downloads mail from the server's maildrop
Port 123: NTP — UDP; clock synchronisation
Port 137: NetBIOS Name Service — UDP (also registered on TCP); NetBIOS name lookups
Port 139: NetBIOS Session Service — TCP; the pre-445 route for Windows file sharing
Port 143: IMAP — TCP; 143/udp is Reserved, not an IMAP port
Port 161: SNMP agent — UDP; the port a manager polls
Port 162: SNMP trap / notification receiver — UDP
Port 179: BGP — TCP; the routing protocol run between autonomous systems
Port 389: LDAP — TCP (registered on UDP too); plaintext directory access
Port 443: HTTPS, HTTP over TLS — TCP; https is registered on UDP too, which is what HTTP/3 uses
Port 445: SMB directly over TCP (registered as microsoft-ds) — Windows file and printer sharing
Port 465: Registered as submissions, SMTP over implicit TLS — TCP; 465/udp is a different service
Port 514: TCP 514 is the BSD shell (rsh) service; UDP 514 is syslog — two different services
Port 520: UDP 520 is RIP, the routing protocol; TCP 520 is registered to efs, not to RIP
Port 587: SMTP message submission from mail clients — TCP; STARTTLS is normal here
Port 636: LDAPS, LDAP over TLS/SSL — TCP
Port 993: IMAPS, IMAP over implicit TLS — TCP; 993/udp is Reserved
Port 995: POP3S, POP3 over implicit TLS — TCP
Port 1433: Microsoft SQL Server, default instance — TCP; the SQL Server Browser uses UDP 1434
Port 1521: Oracle database listener by convention — TCP; IANA registers 1521 to nCube License Manager

Download all 36 cards — $2.99

The printable and every card unlocked to play — $4.28 bought separately, $2.99 together. One payment, no renewal, no account. Or take every deck: Study Pack, $11.99 a month — all 78 decks, all 7,178 cards, every printable, no ads. 5 single decks costs more than one month.

Includes every card unlocked to play online — $4.28 bought separately. One payment, no account, no renewal.

Same price, opens in the editor. Reword any card, add your own, print it your way.

Play it online insteadThe first 30 cards are free to play, with no account.Study Pack — $11.99/monthAll 78 decks and every printable.

Questions

How do I print them double-sided?: Double-sided, flip on the long edge. Every front sheet is followed by its own already-mirrored back sheet, so print them in the order they come and every answer lands on its own card.
Can I edit the cards?: Yes, and that is half the point. Once you own the deck, the "Buy & edit" button here opens all 36 cards in the free flash card maker on this site — reword a definition, delete the ones you do not teach, add your own, and print at anything from two to nine cards a page, rather than the fixed eight of the PDF.
Can I print a set for every student?: Yes. Personal and classroom licence: unlimited printing, every class you teach, every year you teach it. It does not cover reselling the file or passing it on to a colleague.
What if I find a card that is wrong?: Tell us and we fix it, and we publish what changed. We have withdrawn a whole deck from sale for being out of date rather than quietly patch it.
Do I need an account?: No. $2.99 at Stripe, the file downloads on the way back, and the deck stays unlocked in this browser.