> For the complete documentation index, see [llms.txt](https://mmems.gitbook.io/calepin/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mmems.gitbook.io/calepin/network.md). # Network * [Errata Security: Falsehoods programmers believe about networks](https://web.archive.org/web/20210411013500/https://blog.erratasec.com/2012/06/falsehoods-programmers-believe-about.html#.YHJSSHnS9qs) * [BBR: Congestion-Based Congestion Control - ACM Queue](https://queue.acm.org/detail.cfm?id=3022184) ### DNS ``` 8.8.8.8 8.8.4.4 2001:4860:4860::8888 2001:4860:4860::8844 208.67.222.222 208.67.220.220 2620:0:ccc::2 2620:0:ccd::2 ``` * [Get Started | Public DNS | Google Developers](https://developers.google.com/speed/public-dns/docs/using#google_public_dns_ip_addresses) * [IPv6 | OpenDNS](https://www.opendns.com/about/innovations/ipv6/) * [Use OpenDNS](https://use.opendns.com/) * `cat /etc/resolv.conf` * [Non-responsive DNS server or invalid DNS configuration can cause long delay before webpages load - Apple Support](https://support.apple.com/en-au/HT203244) * [domain name system - dig works but ping does not resolve host - Server Fault](https://serverfault.com/questions/813158/dig-works-but-ping-does-not-resolve-host) * [DNS Lecture Notes: contents](http://www-inf.int-evry.fr/~hennequi/CoursDNS/NOTES-COURS_eng/) #### DNS Record ```dns-zone bar.example.com. CNAME foo.example.com. foo.example.com. A 192.0.2.23 @ IN TXT "some text" ``` RR: DNS Resource Record > A DNS zone file contains the list of all Resource Records in the DNS zone. Format is defined in RFC1035 page 33 with an addendum in RFC2308. A unique SOA RR and at least one NS RR for the zone name are required. A complete RR is a quintuplet {FQDN\_NAME, TTL, CLASS, TYPE, RDATA} which can be in abbreviated form in some cases. > > * Comments start with a semicolon `;` and go to the end of line. > * Empty lines are allowed; any combination of tabs and spaces acts as a delimiter. > * RR are defined line by line as : > * `[Name] [TTL] [CLASS] TYPE RDATA` > * if no `Name`, the name is taken from the last stated RR > * if `Name` exists, it starts at the first character of the line > * if `Name` is not dot-terminated (non FQDN), the default domain name defined by `$ORIGIN` directives is concatenated to `Name` > * if no `TTL`, the TTL is defined by `$TTL` directives. > * if no `CLASS`, the CLASS is taken from the last stated RR > * `TTL` and `CLASS` can be exchanged. > * `$TTL integer_value` sets the default value of TTL for following RRs in file (RFC2308, bind>8.1) > * `$ORIGIN fqdn_name` sets the default value of domain name for following RRs in file. Initially, in BIND, the value is set to the current zone name. > * `$INCLUDE filename` inserts the named file into the current file. NB: be careful about value of `$TTL` or `$ORIGIN` after a `$INCLUDE` > * `@` is used to denote the current default domain name. > * `(` and `)` are used to group data that crosses a line boundary. Line terminations are not recognized within parentheses > * `\` is used to quote special characters. Ex : `\.` can be used to place a dot character in a label; `\223` is the 8-bit character corresponding to decimal value 223. > > Stylistic hints: > > * Organize RR : Start with SOA, NS and MX of the zone, continue with delegation (NS) and glue. Group RR by names. > * Comments are useful > * Use spaces or tabulations for vertical alignment > * Start file with a `$ORIGIN` and a `$TTL` > * Try to avoid writing of the zone name in the file > * Generate serial number in SOA as : year/month/day/version 4+2+2+2. > * **BE CAREFUL**: Modify the serial number each time the master file is modified `CNAME` can't be used for apex domain (aka bare domain or naked domain, ex: example.com): * [networking - How to overcome root domain CNAME restrictions? - Stack Overflow](https://stackoverflow.com/questions/656009/how-to-overcome-root-domain-cname-restrictions) * [Why a domain’s root can’t be a CNAME — and other tidbits about the DNS](https://www.freecodecamp.org/news/why-cant-a-domain-s-root-be-a-cname-8cbab38e5f5c/) See also: * [domain name system - What's the meaning of '@' in a DNS zone file? - Server Fault](https://serverfault.com/questions/83874/whats-the-meaning-of-in-a-dns-zone-file) * [Zone file — Wikipedia](https://en.wikipedia.org/wiki/Zone_file) * [List of DNS record types — Wikipedia](https://en.wikipedia.org/wiki/List_of_DNS_record_types) * [Frequent Questions: DNS Records — Gandi Documentation documentation](https://docs.gandi.net/en/domain_names/faq/dns_records.html#do-you-have-examples-of-dns-records) - DNS records exampels ### Wake-on-LAN * [Making a Linux home server sleep on idle and wake on demand — the simple way | Daniel P. Gross](https://web.archive.org/web/20230420192730/https://dgross.ca/blog/linux-home-server-auto-sleep/) * [Wake-on-LAN - Wikipedia](https://en.wikipedia.org/wiki/Wake-on-LAN) ### IP address * 0: 127.0.0.1 (or 0.0.0.0 on macOS) * 10.50.1: 10.50.0.1 * 10.0.513: 10.0.2.1 * 167772673: 10.0.2.1 * A000201: 10.0.2.1 * 10.0.2.010: 10.0.2.8 * [There’s more than one way to write an IP address](https://web.archive.org/web/20230505170552/https://ma.ttias.be/theres-more-than-one-way-to-write-an-ip-address/) is translated to (then the server redirect to Google Search homepage) 32-bit url 0x1000000111010011010000101100011 == 1089053027 == (64 << 24) + (233 << 16) + (161 << 8) + 99 Supported in Firefox, Chrome, IE * [Dot-decimal notation - Wikipedia](https://en.wikipedia.org/wiki/Dot-decimal_notation)