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Questions tagged [ttl]

Time To Live is a mechanism to prevent messages from traversing the network indefinitely

Every IP packet has a Time To Live, it is a counter that gets deducted when it passes a router. It prevents a packet from traversing the network endlessly. If the packets TTL reaches 0 it gets discarded. TTL can be a timestamp or a counter.

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Differences of the TTL value in Tracert and Ping

When I ping localhost on my Windows XP system, the TTL value returned is 128 and it shows me that the default TTL value in the ping for my system is 128. Then when I ping google.com the returned TTL value is 45, and I assume it means that (128 -…
Saba Jamalian
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Using a low TTL to help prevent extended periods of downtime

Is it feasible to set my domain's TTL to a very low value (a couple of minutes) so that, if my main host goes down for an extended period of time, I can update the DNS records in my main host to point to my secondary host's IP, thus directing new…
AmIDoingThisRight
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How does DNS TTL work in chained CNAME configurations?

I have a DNS config that looks something like this: www.example.com 600 IN CNAME prod.myzone.l2.company.example prod.myzone.l2.company.example 600 IN CNAME…
Drew Shafer
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DNS TTL for a record differs between authoritative server, resolver and client

Here's my scenario: I have an office which connects to AWS via a VPN tunnel to access some EC2 instances. The office computers use AWS Route 53 via the VPN tunnel to resolve a private hosted zone. The private hosted zone contains A records of…
KFM
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Ubuntu transmits TTL 0 multicast packets

IP packets with TTL 0 shall not leave host. But when I start application which multicasts UDP packets with TTL 0, I see packets with TTL 0 leaving host for few seconds, and coming to normal behavior of TTL 0. This most likely happens after reboot…
nullptr
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DDNS + DHCPD : Once lease runs out, does DNS entry get removed?

Once there are several hundred adhoc machines being brought up, each with a unique name. Their hostname gets added to the DNS. Then upon TTL expiring, will the DNS entry still be reachable, or if the host has been down for some-time, it [dns-entry]…
romant
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set long ttl on host records before nameserver change?

I'm trying to move DNS from GD to route 53 and it seems impossible to avoid downtime, even with identical zone files in both location. From my experiments, as soon as I change to 'custom' nameservers in GoDaddy they stop answering DNS requests, and…
Lance Magnum
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configuring TTL from 1800 sec to 86400 sec on Ubuntu, nginx server

I deployed an app to Digital Ocean Ubuntu server. The app is running on NGINX. My Domain registar sent me the messages that "TTL can't be less than 86400 sec on nameservers" It is currently 1800 sec by default from Digital Ocean. Can someone advice…
codegirl
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DNS zone settings before a change

I'm completely changing our WAN interface addressing (new ISP). Which DNS zone adjustments should I make to the various parameters (TTL, expire, etc.) to help propagate the changes out to the Internet in the quickest manner? I hacve a week until the…
AaplMike
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Migrating DNS provider when having high NS-record TTL

I have recently migrated one of my .com-domain zones from DNS provider A to DNS provider B, however the TTL on the NS-records for the zone on provider A is very high = 432000 (5 days), and thus I feel sad thinking that I might have to keep (and…
Johan Thomsen
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Why is TTL increasing? (and generally behaving erratically)

Summary: TTL is not decremented when pinging hosts on a "network path" My laptop (10.10.13.10) is connected via OpenVPN to a server (10.10.13.1) which hosts several network interfaces. One of them is 10.10.10.254, the gateway to the 10.10.10.0/24…
WoJ
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Possible issues of switching DNS back and forth quickly

I don't have a ton of knowledge about DNS so I want to be as cautious as possible before I pull the trigger on a re-point. Scenario I am doing a simple migration of a website from one server to another. During downtime I want to do the DNS switch to…
Jared Eitnier
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Fast switching CNAME

Is it possible to make CNAME's switch it's data every minute (or possibly even shorter) ? I'm currently trying to make something that changes my CNAME every minute but i have no idea if this is even possible. So far i have tried different values for…
Maxim
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NSCD TTL and DNS TTL, which one is stronger?

I've configured many servers in my company to work with NSCD for local caching of hosts and in order to lower traffic to the local DNS servers as well as return a quicker DNS response when possible. I've configured nscd like so and only using it for…
Itai Ganot
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Correctly calculate DNS TTL from host -a output

I'm trying to figure out how TTLs are handled in DNS (in the end I'm trying to figure out the fastest way to switch over a domain), but somehow I'm stuck in interpreting TTL values. For example I moved a domain today which had the following DNS…
s1lv3r
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