fabrice/scripts-fabq
fabrice/scripts-fabq
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

feat(dns): add comprehensive DNS notes

Browse Source 
- Documented commands for flushing DNS cache using `resolvectl` and `systemd-resolve`.
- Included instructions for enabling and restarting `systemd-resolved` service.
- Added usage examples for `dig` and `nslookup` to query DNS records.
- Provided contextual explanations and legacy tool considerations.
This commit is contained in:
Fabrice Quenneville 2024-12-05 15:49:54 -05:00
parent cd1db53397
commit 115eec5c62
1 changed files with 64 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
notes/dns.md Normal file
View File

@ -0,0 +1,64 @@
# DNS
## Table of Contents
- [DNS](#dns)
- [Table of Contents](#table-of-contents)
- [Flush DNS Cache](#flush-dns-cache)
- [systemctl](#systemctl)
- [dig](#dig)
- [nslookup](#nslookup)
## Flush DNS Cache
- Clear the DNS cache to ensure that the system resolves domain names with the most up-to-date information.
```bash
resolvectl flush-caches
systemd-resolve --flush-caches
```
- Use `resolvectl` for newer systems or `systemd-resolve` for older systems (pre-2020).
## systemctl
- This command enables the `systemd-resolved` service if it is not already running, ensuring DNS resolution through `systemd`.
```bash
systemctl enable systemd-resolved.service
```
**Explanation of the command:**
- `systemd-resolve --flush-caches`: This command clears the DNS cache maintained by `systemd-resolved`, which can help resolve issues with outdated or incorrect DNS entries.
- After flushing the cache, it may be necessary to restart the `systemd-resolved` service to ensure proper operation.
```bash
systemctl restart systemd-resolved
service systemd-resolved restart
```
- To restart the service, use `systemctl restart systemd-resolved` (preferred). The `service` command is available but is considered legacy.
## dig
```bash
dig domain.com
dig +short NS domain.com
```
## nslookup
- `nslookup` is a legacy tool but still useful for querying DNS. You can also specify custom DNS servers, such as `1.1.1.1` (Cloudflare) or `8.8.8.8` (Google), to query DNS directly without using the system’s default resolver.
```bash
nslookup domain.com
nslookup -q=cname domain.com
nslookup -q=cname domain.com 1.1.1.1
nslookup -q=cname domain.com 8.8.8.8
```
```bash
nslookup -q=mx domain.com
nslookup -q=txt domain.com
```