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Includes MAC address and ARP/IP-to-MAC concepts, a reference of well-known inbound ports with security notes, and quick guides for IPv4 subnetting using CIDR, subnet masks, host address ranges, and wildcard values for /16 and /24 practice tables. Suitable for fast study and troubleshooting.",{"@graph":63,"@context":119},[64,80,102],{"@type":65,"itemListElement":66},"BreadcrumbList",[67,71,74,77],{"item":68,"name":69,"@type":70,"position":9},"https://docshare.wps.com","Home","ListItem",{"item":72,"name":10,"@type":70,"position":73},"https://docshare.wps.com/template/",2,{"item":75,"name":11,"@type":70,"position":76},"https://docshare.wps.com/template/presentations/",3,{"item":78,"name":59,"@type":70,"position":79},"https://docshare.wps.com/template/network-fundamentals-osi-ip-model-layers-ipv4-subnetting/572490/",4,{"url":78,"name":59,"@type":81,"image":82,"author":87,"headline":59,"publisher":90,"fileFormat":93,"inLanguage":57,"description":61,"dateModified":94,"datePublished":95,"encodingFormat":93,"isAccessibleForFree":96,"interactionStatistic":97},"DigitalDocument",{"url":83,"@type":84,"width":85,"height":86},"https://docshare.wps.com/thumbnails/network-fundamentals-osi-ip-model-layers-ipv4-subnetting/572490.png","ImageObject",442,249,{"name":88,"@type":89},"Eliana","Person",{"url":68,"name":91,"@type":92},"DocShare","Organization","application/pdf","2026-10-22","2026-10-13",true,{"@type":98,"interactionType":99,"userInteractionCount":101},"InteractionCounter",{"@type":100},"ViewAction",6,{"@type":103,"mainEntity":104},"FAQPage",[105,111,115],{"name":106,"@type":107,"acceptedAnswer":108},"How do OSI layers relate to IP model layers and addressing concepts?","Question",{"text":109,"@type":110},"The document maps OSI layers to functions and corresponding address types such as Data for application-layer data, Port for transport, and IP Address for the network layer, along with logical routing and segmentation descriptions.","Answer",{"name":112,"@type":107,"acceptedAnswer":113},"What are the well-known inbound ports and the key security cautions mentioned?",{"text":114,"@type":110},"It lists common inbound ports (e.g., FTP 20/21, SSH 22, Telnet 23, DNS 53, HTTP 80, HTTPS 443) and flags several as insecure, recommending alternatives like SFTP/SCP and SSH/HTTPS.",{"name":116,"@type":107,"acceptedAnswer":117},"How is IPv4 subnetting performed using CIDR for /16 and /24?",{"text":118,"@type":110},"It provides CIDR notation and corresponding subnet masks, then summarizes IP address counts and subnet counts for each CIDR size, including wildcard values used to define matching ranges. Practice tables are included for /16 and /24.","https://schema.org",{"og:url":78,"og:type":121,"og:title":59,"og:site_name":91,"og:description":61},"article",{"robots":123,"canonical":78},"index,follow",{"doc_id":125,"site_id":56},572490,1792022684,{"code":4,"msg":5,"data":128},{"doc_id":125,"user_id":129,"nickname":88,"user_avatar":130,"doc_module":9,"category_id":8,"category_name":11,"doc_title":59,"doc_description":61,"doc_content":131,"file_id":132,"file_url":133,"file_type":134,"file_size":135,"view_count":101,"is_deleted":4,"is_public":9,"is_downloadable":9,"audit_status":9,"page_count":73,"language":136,"language_code":57,"site_id":56,"html_lang":57,"table_of_contents":137,"faqs":138,"seo_title":139,"seo_description":61,"update_tm":140,"read_time":9},4398048949847,"https://ap-avatar.wpscdn.com/avatar/400002536579ef2da7f?_k=1778318612642679267","OSI and IP Model Layers  \n\n| Layer |  | OSI | IP Model | Address | Use | Object Name | Protocols, Standards |\n| --- | --- | --- | --- | --- | --- | --- | --- |\n| 7 | Application |  | Application |  | The function which needs network access | Data | BGP, OSPF, IMAP, DNS, NTP, [HTTP](HTTP) , FTP |\n| 6 | Presentation |  |  |  | Works together with Application . Responsible for translation and serialization of data between applications |  |  |\n| 5 | Session |  | Transport | Session ID | Connection Mgmt, Ports, Synchronization,\u003Cbr>Authentication |  | NFS, SQL, PAP, RPC |\n| 4 | Transport |  |  | Port | Setup and manage conversation flow | Segment | TCP - RFC 9293, UDP - RFC 768 |\n| 3 | Network |  | Internet | IP Address | Logical addressing and routing of segments | Packet | IPv4 - RFC 791\u003Cbr>IPv6 - RFC 8200 |\n| 2 | Data-Link |  | Network Access | MAC Address | Encode the data, manage access to the medium | Frame | IEEE 802.3 (Ethenet),\u003Cbr>IEEE 802.11 (Wi-Fi) |\n| 1 | Physical |  |  |  | Transmit and carry the data | Bit/Symbol |  |\n\nMAC Address Table : MAC Addresses to Last Known Interface (Based on Source Address) ARP Table : IP Address to MAC Address  \nWell Known Ports from the Internet Assigned Numbers Authority (IANA)  \n\n| Protocol | Common Inbound Port | TCP/UDP | Notes |\n| --- | --- | --- | --- |\n| FTP | 20 data,21 control | TCP | Insecure . Use SFTP/SCP |\n| SSH (SFTP, SCP) | 22 | TCP | SFTP and SCP use SSH to establish session |\n| Telnet | 23 | TCP | Insecure . Use SSH |\n| SMTP | 25 | TCP |  |\n| DNS | 53 | Both |  |\n| DHCP | 67,68 | UDP |  |\n| TFTP | 69 | UDP | Insecure . Use SFTP/SCP |\n| [HTTP](HTTP) | 80 | Both | Insecure . Use [HTTPS](HTTPS) |\n| POP3 | 110 | TCP |  |\n| NTP | 123 | UDP |  |\n| IMAP4 | 143 | TCP |  |\n| SNMP | 161, 162 SNMP Trap | UDP |  |\n| LDAP | 389 | TCP |  |\n| [HTTPS](HTTPS) | 443 | Both |  |\n| Syslog | 514 | UDP |  |\n| RDP | 3389 | Both |  |\n\nIPv4 Subnetting /16  \n\n|  |  |  |  |  |  |  |  |  |\n| --- | --- | --- | --- | --- | --- | --- | --- | --- |\n| CIDR Notation | /17 | /18 | /19 | /20 | /21 | /22 | /23 | /24 |\n| Subnet Mask | [255.255.128.0](255.255.128.0) | [255.255.192.0](255.255.192.0) | [255.255.224.0](255.255.224.0) | [255.255.240.0](255.255.240.0) | [255.255.248.0](255.255.248.0) | [255.255.252.0](255.255.252.0) | [255.255.254.0](255.255.254.0) | [255.255.255.0](255.255.255.0) |\n| IP Addresses | 32768 | 16384 | 8192 | 4096 | 2048 | 1024 | 512 | 256 |\n| Subnets /16 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 |\n| Subnets /24 |  |  |  |  |  |  |  | 1 |\n| Wildcard |  |  |  |  |  |  |  | 0 |\n\nIPv4 Subnetting /24  \n\n|  |  |  |  |  |  |  |  |  |\n| --- | --- | --- | --- | --- | --- | --- | --- | --- |\n| CIDR Notation | /25 | /26 | /27 | /28 | /29 | /30 | /31 | /32 |\n| Subnet Mask | [255.255.255.128](255.255.255.128) | [255.255.255.192](255.255.255.192) | [255.255.255.224](255.255.255.224) | [255.255.255.240](255.255.255.240) | [255.255.255.248](255.255.255.248) | [255.255.255.252](255.255.255.252) | [255.255.255.254](255.255.255.254) | [255.255.255.255](255.255.255.255) |\n| IP Addresses | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |\n| Subnets /16 | 512 | 1024 | 2048 | 4096 | 8192 | 16384 | 32768 | 65536 |\n| Subnets /24 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | [HOST} |\n| Wildcard | 1 | 3 | 7 | 15 | 31 | 63 | 127 | 255 |\n\nJonathan Davis  \n[jd@subnetwork.me](jd@subnetwork.me)  \n[https://subnetwork.me](https://subnetwork.me)  \nVersion 2024.2.4  \nIPv4 Subnetting /16 Practice 1  \n\n|  |  |  |  |  |  |  |  |  |\n| --- | --- | --- | --- | --- | --- | --- | --- | --- |\n| CIDR Notation | /17 | /18 | /19 | /20 | /21 | /22 | /23 | /24 |\n| Subnet Mask |  |  |  |  |  |  |  |  |\n| IP Addresses |  |  |  |  |  |  |  |  |\n| Subnets /16 |  |  |  |  |  |  |  |  |\n| Subnets /24 |  |  |  |  |  |  |  |  |\n| Wildcard |  |  |  |  |  |  |  |  |\n\nIPv4 Subnetting /24 Practice 1  \n\n|  |  |  |  |  |  |  |  |  |\n| --- | --- | --- | --- | --- | --- | --- | --- | --- |\n| CIDR Notation | /25 | /26 | /27 | /28 | /29 | /30 | /31 | /32 |\n| Subnet Mask |  |  | ","cbCaii7km6SBN8IG","https://ap.wps.com/l/cbCaii7km6SBN8IG","pdf",177425,"English","# OSI and IP Model Layers\n## Layer mapping, addresses, and protocols\n## Address resolution: MAC table and ARP\n# Well-known Internet Ports (IANA)\n## Common inbound ports and security notes\n# IPv4 Subnetting (CIDR)\n## /16 subnetting ranges and masks\n## /24 subnetting ranges and masks\n# Subnetting Practice Tables\n## /16 practice 1-3\n## /24 practice 1-3","[{\"question\":\"How do OSI layers relate to IP model layers and addressing concepts?\",\"answer\":\"The document maps OSI layers to functions and corresponding address types such as Data for application-layer data, Port for transport, and IP Address for the network layer, along with logical routing and segmentation descriptions.\"},{\"question\":\"What are the well-known inbound ports and the key security cautions mentioned?\",\"answer\":\"It lists common inbound ports (e.g., FTP 20/21, SSH 22, Telnet 23, DNS 53, HTTP 80, HTTPS 443) and flags several as insecure, recommending alternatives like SFTP/SCP and SSH/HTTPS.\"},{\"question\":\"How is IPv4 subnetting performed using CIDR for /16 and /24?\",\"answer\":\"It provides CIDR notation and corresponding subnet masks, then summarizes IP address counts and subnet counts for each CIDR size, including wildcard values used to define matching ranges. Practice tables are included for /16 and /24.\"}]","Network Fundamentals - OSI & IP Model Layers - IPv4 Subnetting | PDF",1791927728]